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diff --git a/doc/intro/Makefile b/doc/intro/Makefile new file mode 100644 index 0000000..939cd6c --- /dev/null +++ b/doc/intro/Makefile @@ -0,0 +1,13 @@ +# @(#)Makefile 8.2 (Berkeley) 2/28/94 + +DIR= smm/09.sendmail +SRCS= intro.me +MACROS= -me + +all: intro.ps + +intro.ps: ${SRCS} + rm -f ${.TARGET} + ${PIC} ${SRCS} | ${ROFF} > ${.TARGET} + +.include <bsd.doc.mk> diff --git a/doc/intro/intro.me b/doc/intro/intro.me new file mode 100644 index 0000000..0406bb1 --- /dev/null +++ b/doc/intro/intro.me @@ -0,0 +1,1478 @@ +.\" Copyright (c) 1983 Eric P. Allman +.\" Copyright (c) 1988, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)intro.me 8.2 (Berkeley) 11/27/93 +.\" +.\" pic -Pxx intro.me | ditroff -me -Pxx +.eh 'SMM:9-%''SENDMAIL \*- An Internetwork Mail Router' +.oh 'SENDMAIL \*- An Internetwork Mail Router''SMM:9-%' +.nr si 3n +.if n .ls 2 +.+c +.(l C +.sz 14 +SENDMAIL \*- An Internetwork Mail Router +.sz +.sp +Eric Allman* +.sp 0.5 +.i +University of California, Berkeley +Mammoth Project +.)l +.sp +.(l F +.ce +ABSTRACT +.sp \n(psu +Routing mail through a heterogenous internet presents many new +problems. Among the worst of these is that of address mapping. +Historically, this has been handled on an +.i "ad hoc" +basis. However, +this approach has become unmanageable as internets grow. +.sp \n(psu +Sendmail acts a unified "post office" to which all mail can be +submitted. Address interpretation is controlled by a production +system, which can parse both domain-based addressing and old-style +.i "ad hoc" +addresses. +The production system is powerful +enough to rewrite addresses in the message header to conform to the +standards of a number of common target networks, including old +(NCP/RFC733) Arpanet, new (TCP/RFC822) Arpanet, UUCP, and Phonenet. +Sendmail also implements an SMTP server, message +queueing, and aliasing. +.)l +.sp 2 +.(f +*A considerable part of this work +was done while under the employ +of the INGRES Project +at the University of California at Berkeley +and at Britton Lee. +.)f +.pp +.i Sendmail +implements a general internetwork mail routing facility, +featuring aliasing and forwarding, +automatic routing to network gateways, +and flexible configuration. +.pp +In a simple network, +each node has an address, +and resources can be identified +with a host-resource pair; +in particular, +the mail system can refer to users +using a host-username pair. +Host names and numbers have to be administered by a central authority, +but usernames can be assigned locally to each host. +.pp +In an internet, +multiple networks with different characterstics +and managements +must communicate. +In particular, +the syntax and semantics of resource identification change. +Certain special cases can be handled trivially +by +.i "ad hoc" +techniques, +such as +providing network names that appear local to hosts +on other networks, +as with the Ethernet at Xerox PARC. +However, the general case is extremely complex. +For example, +some networks require point-to-point routing, +which simplifies the database update problem +since only adjacent hosts must be entered +into the system tables, +while others use end-to-end addressing. +Some networks use a left-associative syntax +and others use a right-associative syntax, +causing ambiguity in mixed addresses. +.pp +Internet standards seek to eliminate these problems. +Initially, these proposed expanding the address pairs +to address triples, +consisting of +{network, host, resource} +triples. +Network numbers must be universally agreed upon, +and hosts can be assigned locally +on each network. +The user-level presentation was quickly expanded +to address domains, +comprised of a local resource identification +and a hierarchical domain specification +with a common static root. +The domain technique +separates the issue of physical versus logical addressing. +For example, +an address of the form +.q "eric@a.cc.berkeley.arpa" +describes only the logical +organization of the address space. +.pp +.i Sendmail +is intended to help bridge the gap +between the totally +.i "ad hoc" +world +of networks that know nothing of each other +and the clean, tightly-coupled world +of unique network numbers. +It can accept old arbitrary address syntaxes, +resolving ambiguities using heuristics +specified by the system administrator, +as well as domain-based addressing. +It helps guide the conversion of message formats +between disparate networks. +In short, +.i sendmail +is designed to assist a graceful transition +to consistent internetwork addressing schemes. +.sp +.pp +Section 1 discusses the design goals for +.i sendmail . +Section 2 gives an overview of the basic functions of the system. +In section 3, +details of usage are discussed. +Section 4 compares +.i sendmail +to other internet mail routers, +and an evaluation of +.i sendmail +is given in section 5, +including future plans. +.sh 1 "DESIGN GOALS" +.pp +Design goals for +.i sendmail +include: +.np +Compatibility with the existing mail programs, +including Bell version 6 mail, +Bell version 7 mail +[UNIX83], +Berkeley +.i Mail +[Shoens79], +BerkNet mail +[Schmidt79], +and hopefully UUCP mail +[Nowitz78a, Nowitz78b]. +ARPANET mail +[Crocker77a, Postel77] +was also required. +.np +Reliability, in the sense of guaranteeing +that every message is correctly delivered +or at least brought to the attention of a human +for correct disposal; +no message should ever be completely lost. +This goal was considered essential +because of the emphasis on mail in our environment. +It has turned out to be one of the hardest goals to satisfy, +especially in the face of the many anomalous message formats +produced by various ARPANET sites. +For example, +certain sites generate improperly formated addresses, +occasionally +causing error-message loops. +Some hosts use blanks in names, +causing problems with +UNIX mail programs that assume that an address +is one word. +The semantics of some fields +are interpreted slightly differently +by different sites. +In summary, +the obscure features of the ARPANET mail protocol +really +.i are +used and +are difficult to support, +but must be supported. +.np +Existing software to do actual delivery +should be used whenever possible. +This goal derives as much from political and practical considerations +as technical. +.np +Easy expansion to +fairly complex environments, +including multiple +connections to a single network type +(such as with multiple UUCP or Ether nets +[Metcalfe76]). +This goal requires consideration of the contents of an address +as well as its syntax +in order to determine which gateway to use. +For example, +the ARPANET is bringing up the +TCP protocol to replace the old NCP protocol. +No host at Berkeley runs both TCP and NCP, +so it is necessary to look at the ARPANET host name +to determine whether to route mail to an NCP gateway +or a TCP gateway. +.np +Configuration should not be compiled into the code. +A single compiled program should be able to run as is at any site +(barring such basic changes as the CPU type or the operating system). +We have found this seemingly unimportant goal +to be critical in real life. +Besides the simple problems that occur when any program gets recompiled +in a different environment, +many sites like to +.q fiddle +with anything that they will be recompiling anyway. +.np +.i Sendmail +must be able to let various groups maintain their own mailing lists, +and let individuals specify their own forwarding, +without modifying the system alias file. +.np +Each user should be able to specify which mailer to execute +to process mail being delivered for him. +This feature allows users who are using specialized mailers +that use a different format to build their environment +without changing the system, +and facilitates specialized functions +(such as returning an +.q "I am on vacation" +message). +.np +Network traffic should be minimized +by batching addresses to a single host where possible, +without assistance from the user. +.pp +These goals motivated the architecture illustrated in figure 1. +.(z +.hl +.ie t \ +\{\ +.ie !"\*(.T"" \ +\{\ +.PS +boxht = 0.5i +boxwid = 1.0i + + down +S: [ + right + S1: box "sender1" + move + box "sender2" + move + S3: box "sender3" + ] + arrow +SM: box "sendmail" wid 2i ht boxht + arrow +M: [ + right + M1: box "mailer1" + move + box "mailer2" + move + M3: box "mailer3" + ] + + arrow from S.S1.s to 1/2 between SM.nw and SM.n + arrow from S.S3.s to 1/2 between SM.n and SM.ne + + arrow from 1/2 between SM.sw and SM.s to M.M1.n + arrow from 1/2 between SM.s and SM.se to M.M3.n +.PE +.\} +.el \ +. sp 18 +.\} +.el \{\ +.(c ++---------+ +---------+ +---------+ +| sender1 | | sender2 | | sender3 | ++---------+ +---------+ +---------+ + | | | + +----------+ + +----------+ + | | | + v v v + +-------------+ + | sendmail | + +-------------+ + | | | + +----------+ + +----------+ + | | | + v v v ++---------+ +---------+ +---------+ +| mailer1 | | mailer2 | | mailer3 | ++---------+ +---------+ +---------+ +.)c +.\} + +.ce +Figure 1 \*- Sendmail System Structure. +.hl +.)z +The user interacts with a mail generating and sending program. +When the mail is created, +the generator calls +.i sendmail , +which routes the message to the correct mailer(s). +Since some of the senders may be network servers +and some of the mailers may be network clients, +.i sendmail +may be used as an internet mail gateway. +.sh 1 "OVERVIEW" +.sh 2 "System Organization" +.pp +.i Sendmail +neither interfaces with the user +nor does actual mail delivery. +Rather, +it collects a message +generated by a user interface program (UIP) +such as Berkeley +.i Mail , +MS +[Crocker77b], +or MH +[Borden79], +edits the message as required by the destination network, +and calls appropriate mailers +to do mail delivery or queueing for network transmission\**. +.(f +\**except when mailing to a file, +when +.i sendmail +does the delivery directly. +.)f +This discipline allows the insertion of new mailers +at minimum cost. +In this sense +.i sendmail +resembles the Message Processing Module (MPM) +of [Postel79b]. +.sh 2 "Interfaces to the Outside World" +.pp +There are three ways +.i sendmail +can communicate with the outside world, +both in receiving and in sending mail. +These are using the conventional UNIX +argument vector/return status, +speaking SMTP over a pair of UNIX pipes, +and speaking SMTP over an interprocess(or) channel. +.sh 3 "Argument vector/exit status" +.pp +This technique is the standard UNIX method +for communicating with the process. +A list of recipients is sent in the argument vector, +and the message body is sent on the standard input. +Anything that the mailer prints +is simply collected and sent back to the sender +if there were any problems. +The exit status from the mailer is collected +after the message is sent, +and a diagnostic is printed if appropriate. +.sh 3 "SMTP over pipes" +.pp +The SMTP protocol +[Postel82] +can be used to run an interactive lock-step interface +with the mailer. +A subprocess is still created, +but no recipient addresses are passed to the mailer +via the argument list. +Instead, they are passed one at a time +in commands sent to the processes standard input. +Anything appearing on the standard output +must be a reply code +in a special format. +.sh 3 "SMTP over an IPC connection" +.pp +This technique is similar to the previous technique, +except that it uses a 4.2bsd IPC channel +[UNIX83]. +This method is exceptionally flexible +in that the mailer need not reside +on the same machine. +It is normally used to connect to a sendmail process +on another machine. +.sh 2 "Operational Description" +.pp +When a sender wants to send a message, +it issues a request to +.i sendmail +using one of the three methods described above. +.i Sendmail +operates in two distinct phases. +In the first phase, +it collects and stores the message. +In the second phase, +message delivery occurs. +If there were errors during processing +during the second phase, +.i sendmail +creates and returns a new message describing the error +and/or returns an status code +telling what went wrong. +.sh 3 "Argument processing and address parsing" +.pp +If +.i sendmail +is called using one of the two subprocess techniques, +the arguments +are first scanned +and option specifications are processed. +Recipient addresses are then collected, +either from the command line +or from the SMTP +RCPT command, +and a list of recipients is created. +Aliases are expanded at this step, +including mailing lists. +As much validation as possible of the addresses +is done at this step: +syntax is checked, and local addresses are verified, +but detailed checking of host names and addresses +is deferred until delivery. +Forwarding is also performed +as the local addresses are verified. +.pp +.i Sendmail +appends each address +to the recipient list after parsing. +When a name is aliased or forwarded, +the old name is retained in the list, +and a flag is set that tells the delivery phase +to ignore this recipient. +This list is kept free from duplicates, +preventing alias loops +and duplicate messages deliverd to the same recipient, +as might occur if a person is in two groups. +.sh 3 "Message collection" +.pp +.i Sendmail +then collects the message. +The message should have a header at the beginning. +No formatting requirements are imposed on the message +except that they must be lines of text +(i.e., binary data is not allowed). +The header is parsed and stored in memory, +and the body of the message is saved +in a temporary file. +.pp +To simplify the program interface, +the message is collected even if no addresses were valid. +The message will be returned with an error. +.sh 3 "Message delivery" +.pp +For each unique mailer and host in the recipient list, +.i sendmail +calls the appropriate mailer. +Each mailer invocation sends to all users receiving the message on one host. +Mailers that only accept one recipient at a time +are handled properly. +.pp +The message is sent to the mailer +using one of the same three interfaces +used to submit a message to sendmail. +Each copy of the message is +prepended by a customized header. +The mailer status code is caught and checked, +and a suitable error message given as appropriate. +The exit code must conform to a system standard +or a generic message +(\c +.q "Service unavailable" ) +is given. +.sh 3 "Queueing for retransmission" +.pp +If the mailer returned an status that +indicated that it might be able to handle the mail later, +.i sendmail +will queue the mail and try again later. +.sh 3 "Return to sender" +.pp +If errors occur during processing, +.i sendmail +returns the message to the sender for retransmission. +The letter can be mailed back +or written in the file +.q dead.letter +in the sender's home directory\**. +.(f +\**Obviously, if the site giving the error is not the originating +site, the only reasonable option is to mail back to the sender. +Also, there are many more error disposition options, +but they only effect the error message \*- the +.q "return to sender" +function is always handled in one of these two ways. +.)f +.sh 2 "Message Header Editing" +.pp +Certain editing of the message header +occurs automatically. +Header lines can be inserted +under control of the configuration file. +Some lines can be merged; +for example, +a +.q From: +line and a +.q Full-name: +line can be merged under certain circumstances. +.sh 2 "Configuration File" +.pp +Almost all configuration information is read at runtime +from an ASCII file, +encoding +macro definitions +(defining the value of macros used internally), +header declarations +(telling sendmail the format of header lines that it will process specially, +i.e., lines that it will add or reformat), +mailer definitions +(giving information such as the location and characteristics +of each mailer), +and address rewriting rules +(a limited production system to rewrite addresses +which is used to parse and rewrite the addresses). +.pp +To improve performance when reading the configuration file, +a memory image can be provided. +This provides a +.q compiled +form of the configuration file. +.sh 1 "USAGE AND IMPLEMENTATION" +.sh 2 "Arguments" +.pp +Arguments may be flags and addresses. +Flags set various processing options. +Following flag arguments, +address arguments may be given, +unless we are running in SMTP mode. +Addresses follow the syntax in RFC822 +[Crocker82] +for ARPANET +address formats. +In brief, the format is: +.np +Anything in parentheses is thrown away +(as a comment). +.np +Anything in angle brackets (\c +.q "<\|>" ) +is preferred +over anything else. +This rule implements the ARPANET standard that addresses of the form +.(b +user name <machine-address> +.)b +will send to the electronic +.q machine-address +rather than the human +.q "user name." +.np +Double quotes +(\ "\ ) +quote phrases; +backslashes quote characters. +Backslashes are more powerful +in that they will cause otherwise equivalent phrases +to compare differently \*- for example, +.i user +and +.i +"user" +.r +are equivalent, +but +.i \euser +is different from either of them. +.pp +Parentheses, angle brackets, and double quotes +must be properly balanced and nested. +The rewriting rules control remaining parsing\**. +.(f +\**Disclaimer: Some special processing is done +after rewriting local names; see below. +.)f +.sh 2 "Mail to Files and Programs" +.pp +Files and programs are legitimate message recipients. +Files provide archival storage of messages, +useful for project administration and history. +Programs are useful as recipients in a variety of situations, +for example, +to maintain a public repository of systems messages +(such as the Berkeley +.i msgs +program, +or the MARS system +[Sattley78]). +.pp +Any address passing through the initial parsing algorithm +as a local address +(i.e, not appearing to be a valid address for another mailer) +is scanned for two special cases. +If prefixed by a vertical bar (\c +.q \^|\^ ) +the rest of the address is processed as a shell command. +If the user name begins with a slash mark (\c +.q /\^ ) +the name is used as a file name, +instead of a login name. +.pp +Files that have setuid or setgid bits set +but no execute bits set +have those bits honored if +.i sendmail +is running as root. +.sh 2 "Aliasing, Forwarding, Inclusion" +.pp +.i Sendmail +reroutes mail three ways. +Aliasing applies system wide. +Forwarding allows each user to reroute incoming mail +destined for that account. +Inclusion directs +.i sendmail +to read a file for a list of addresses, +and is normally used +in conjunction with aliasing. +.sh 3 "Aliasing" +.pp +Aliasing maps names to address lists using a system-wide file. +This file is indexed to speed access. +Only names that parse as local +are allowed as aliases; +this guarantees a unique key +(since there are no nicknames for the local host). +.sh 3 "Forwarding" +.pp +After aliasing, +recipients that are local and valid +are checked for the existence of a +.q .forward +file in their home directory. +If it exists, +the message is +.i not +sent to that user, +but rather to the list of users in that file. +Often +this list will contain only one address, +and the feature will be used for network mail forwarding. +.pp +Forwarding also permits a user to specify a private incoming mailer. +For example, +forwarding to: +.(b +"\^|\|/usr/local/newmail myname" +.)b +will use a different incoming mailer. +.sh 3 "Inclusion" +.pp +Inclusion is specified in RFC 733 [Crocker77a] syntax: +.(b +:Include: pathname +.)b +An address of this form reads the file specified by +.i pathname +and sends to all users listed in that file. +.pp +The intent is +.i not +to support direct use of this feature, +but rather to use this as a subset of aliasing. +For example, +an alias of the form: +.(b +project: :include:/usr/project/userlist +.)b +is a method of letting a project maintain a mailing list +without interaction with the system administration, +even if the alias file is protected. +.pp +It is not necessary to rebuild the index on the alias database +when a :include: list is changed. +.sh 2 "Message Collection" +.pp +Once all recipient addresses are parsed and verified, +the message is collected. +The message comes in two parts: +a message header and a message body, +separated by a blank line. +.pp +The header is formatted as a series of lines +of the form +.(b + field-name: field-value +.)b +Field-value can be split across lines by starting the following +lines with a space or a tab. +Some header fields have special internal meaning, +and have appropriate special processing. +Other headers are simply passed through. +Some header fields may be added automatically, +such as time stamps. +.pp +The body is a series of text lines. +It is completely uninterpreted and untouched, +except that lines beginning with a dot +have the dot doubled +when transmitted over an SMTP channel. +This extra dot is stripped by the receiver. +.sh 2 "Message Delivery" +.pp +The send queue is ordered by receiving host +before transmission +to implement message batching. +Each address is marked as it is sent +so rescanning the list is safe. +An argument list is built as the scan proceeds. +Mail to files is detected during the scan of the send list. +The interface to the mailer +is performed using one of the techniques +described in section 2.2. +.pp +After a connection is established, +.i sendmail +makes the per-mailer changes to the header +and sends the result to the mailer. +If any mail is rejected by the mailer, +a flag is set to invoke the return-to-sender function +after all delivery completes. +.sh 2 "Queued Messages" +.pp +If the mailer returns a +.q "temporary failure" +exit status, +the message is queued. +A control file is used to describe the recipients to be sent to +and various other parameters. +This control file is formatted as a series of lines, +each describing a sender, +a recipient, +the time of submission, +or some other salient parameter of the message. +The header of the message is stored +in the control file, +so that the associated data file in the queue +is just the temporary file that was originally collected. +.sh 2 "Configuration" +.pp +Configuration is controlled primarily by a configuration file +read at startup. +.i Sendmail +should not need to be recomplied except +.np +To change operating systems +(V6, V7/32V, 4BSD). +.np +To remove or insert the DBM +(UNIX database) +library. +.np +To change ARPANET reply codes. +.np +To add headers fields requiring special processing. +.lp +Adding mailers or changing parsing +(i.e., rewriting) +or routing information +does not require recompilation. +.pp +If the mail is being sent by a local user, +and the file +.q .mailcf +exists in the sender's home directory, +that file is read as a configuration file +after the system configuration file. +The primary use of this feature is to add header lines. +.pp +The configuration file encodes macro definitions, +header definitions, +mailer definitions, +rewriting rules, +and options. +.sh 3 Macros +.pp +Macros can be used in three ways. +Certain macros transmit +unstructured textual information +into the mail system, +such as the name +.i sendmail +will use to identify itself in error messages. +Other macros transmit information from +.i sendmail +to the configuration file +for use in creating other fields +(such as argument vectors to mailers); +e.g., the name of the sender, +and the host and user +of the recipient. +Other macros are unused internally, +and can be used as shorthand in the configuration file. +.sh 3 "Header declarations" +.pp +Header declarations inform +.i sendmail +of the format of known header lines. +Knowledge of a few header lines +is built into +.i sendmail , +such as the +.q From: +and +.q Date: +lines. +.pp +Most configured headers +will be automatically inserted +in the outgoing message +if they don't exist in the incoming message. +Certain headers are suppressed by some mailers. +.sh 3 "Mailer declarations" +.pp +Mailer declarations tell +.i sendmail +of the various mailers available to it. +The definition specifies the internal name of the mailer, +the pathname of the program to call, +some flags associated with the mailer, +and an argument vector to be used on the call; +this vector is macro-expanded before use. +.sh 3 "Address rewriting rules" +.pp +The heart of address parsing in +.i sendmail +is a set of rewriting rules. +These are an ordered list of pattern-replacement rules, +(somewhat like a production system, +except that order is critical), +which are applied to each address. +The address is rewritten textually until it is either rewritten +into a special canonical form +(i.e., +a (mailer, host, user) +3-tuple, +such as {arpanet, usc-isif, postel} +representing the address +.q "postel@usc-isif" ), +or it falls off the end. +When a pattern matches, +the rule is reapplied until it fails. +.pp +The configuration file also supports the editing of addresses +into different formats. +For example, +an address of the form: +.(b +ucsfcgl!tef +.)b +might be mapped into: +.(b +tef@ucsfcgl.UUCP +.)b +to conform to the domain syntax. +Translations can also be done in the other direction. +.sh 3 "Option setting" +.pp +There are several options that can be set +from the configuration file. +These include the pathnames of various support files, +timeouts, +default modes, +etc. +.sh 1 "COMPARISON WITH OTHER MAILERS" +.sh 2 "Delivermail" +.pp +.i Sendmail +is an outgrowth of +.i delivermail . +The primary differences are: +.np +Configuration information is not compiled in. +This change simplifies many of the problems +of moving to other machines. +It also allows easy debugging of new mailers. +.np +Address parsing is more flexible. +For example, +.i delivermail +only supported one gateway to any network, +whereas +.i sendmail +can be sensitive to host names +and reroute to different gateways. +.np +Forwarding and +:include: +features eliminate the requirement that the system alias file +be writable by any user +(or that an update program be written, +or that the system administration make all changes). +.np +.i Sendmail +supports message batching across networks +when a message is being sent to multiple recipients. +.np +A mail queue is provided in +.i sendmail. +Mail that cannot be delivered immediately +but can potentially be delivered later +is stored in this queue for a later retry. +The queue also provides a buffer against system crashes; +after the message has been collected +it may be reliably redelivered +even if the system crashes during the initial delivery. +.np +.i Sendmail +uses the networking support provided by 4.2BSD +to provide a direct interface networks such as the ARPANET +and/or Ethernet +using SMTP (the Simple Mail Transfer Protocol) +over a TCP/IP connection. +.sh 2 "MMDF" +.pp +MMDF +[Crocker79] +spans a wider problem set than +.i sendmail . +For example, +the domain of +MMDF includes a +.q "phone network" +mailer, whereas +.i sendmail +calls on preexisting mailers in most cases. +.pp +MMDF and +.i sendmail +both support aliasing, +customized mailers, +message batching, +automatic forwarding to gateways, +queueing, +and retransmission. +MMDF supports two-stage timeout, +which +.i sendmail +does not support. +.pp +The configuration for MMDF +is compiled into the code\**. +.(f +\**Dynamic configuration tables are currently being considered +for MMDF; +allowing the installer to select either compiled +or dynamic tables. +.)f +.pp +Since MMDF does not consider backwards compatibility +as a design goal, +the address parsing is simpler but much less flexible. +.pp +It is somewhat harder to integrate a new channel\** +.(f +\**The MMDF equivalent of a +.i sendmail +.q mailer. +.)f +into MMDF. +In particular, +MMDF must know the location and format +of host tables for all channels, +and the channel must speak a special protocol. +This allows MMDF to do additional verification +(such as verifying host names) +at submission time. +.pp +MMDF strictly separates the submission and delivery phases. +Although +.i sendmail +has the concept of each of these stages, +they are integrated into one program, +whereas in MMDF they are split into two programs. +.sh 2 "Message Processing Module" +.pp +The Message Processing Module (MPM) +discussed by Postel [Postel79b] +matches +.i sendmail +closely in terms of its basic architecture. +However, +like MMDF, +the MPM includes the network interface software +as part of its domain. +.pp +MPM also postulates a duplex channel to the receiver, +as does MMDF, +thus allowing simpler handling of errors +by the mailer +than is possible in +.i sendmail . +When a message queued by +.i sendmail +is sent, +any errors must be returned to the sender +by the mailer itself. +Both MPM and MMDF mailers +can return an immediate error response, +and a single error processor can create an appropriate response. +.pp +MPM prefers passing the message as a structured object, +with type-length-value tuples\**. +.(f +\**This is similar to the NBS standard. +.)f +Such a convention requires a much higher degree of cooperation +between mailers than is required by +.i sendmail . +MPM also assumes a universally agreed upon internet name space +(with each address in the form of a net-host-user tuple), +which +.i sendmail +does not. +.sh 1 "EVALUATIONS AND FUTURE PLANS" +.pp +.i Sendmail +is designed to work in a nonhomogeneous environment. +Every attempt is made to avoid imposing unnecessary constraints +on the underlying mailers. +This goal has driven much of the design. +One of the major problems +has been the lack of a uniform address space, +as postulated in [Postel79a] +and [Postel79b]. +.pp +A nonuniform address space implies that a path will be specified +in all addresses, +either explicitly (as part of the address) +or implicitly +(as with implied forwarding to gateways). +This restriction has the unpleasant effect of making replying to messages +exceedingly difficult, +since there is no one +.q address +for any person, +but only a way to get there from wherever you are. +.pp +Interfacing to mail programs +that were not initially intended to be applied +in an internet environment +has been amazingly successful, +and has reduced the job to a manageable task. +.pp +.i Sendmail +has knowledge of a few difficult environments +built in. +It generates ARPANET FTP/SMTP compatible error messages +(prepended with three-digit numbers +[Neigus73, Postel74, Postel82]) +as necessary, +optionally generates UNIX-style +.q From +lines on the front of messages for some mailers, +and knows how to parse the same lines on input. +Also, +error handling has an option customized for BerkNet. +.pp +The decision to avoid doing any type of delivery where possible +(even, or perhaps especially, local delivery) +has turned out to be a good idea. +Even with local delivery, +there are issues of the location of the mailbox, +the format of the mailbox, +the locking protocol used, +etc., +that are best decided by other programs. +One surprisingly major annoyance in many internet mailers +is that the location and format of local mail is built in. +The feeling seems to be that local mail is so common +that it should be efficient. +This feeling is not born out by +our experience; +on the contrary, +the location and format of mailboxes seems to vary widely +from system to system. +.pp +The ability to automatically generate a response to incoming mail +(by forwarding mail to a program) +seems useful +(\c +.q "I am on vacation until late August...." ) +but can create problems +such as forwarding loops +(two people on vacation whose programs send notes back and forth, +for instance) +if these programs are not well written. +A program could be written to do standard tasks correctly, +but this would solve the general case. +.pp +It might be desirable to implement some form of load limiting. +I am unaware of any mail system that addresses this problem, +nor am I aware of any reasonable solution at this time. +.pp +The configuration file is currently practically inscrutable; +considerable convenience could be realized +with a higher-level format. +.pp +It seems clear that common protocols will be changing soon +to accommodate changing requirements and environments. +These changes will include modifications to the message header +(e.g., [NBS80]) +or to the body of the message itself +(such as for multimedia messages +[Postel80]). +Experience indicates that +these changes should be relatively trivial to integrate +into the existing system. +.pp +In tightly coupled environments, +it would be nice to have a name server +such as Grapvine +[Birrell82] +integrated into the mail system. +This would allow a site such as +.q Berkeley +to appear as a single host, +rather than as a collection of hosts, +and would allow people to move transparently among machines +without having to change their addresses. +Such a facility +would require an automatically updated database +and some method of resolving conflicts. +Ideally this would be effective even without +all hosts being under +a single management. +However, +it is not clear whether this feature +should be integrated into the +aliasing facility +or should be considered a +.q "value added" +feature outside +.i sendmail +itself. +.pp +As a more interesting case, +the CSNET name server +[Solomon81] +provides an facility that goes beyond a single +tightly-coupled environment. +Such a facility would normally exist outside of +.i sendmail +however. +.sh 0 "ACKNOWLEDGEMENTS" +.pp +Thanks are due to Kurt Shoens for his continual cheerful +assistance and good advice, +Bill Joy for pointing me in the correct direction +(over and over), +and Mark Horton for more advice, +prodding, +and many of the good ideas. +Kurt and Eric Schmidt are to be credited +for using +.i delivermail +as a server for their programs +(\c +.i Mail +and BerkNet respectively) +before any sane person should have, +and making the necessary modifications +promptly and happily. +Eric gave me considerable advice about the perils +of network software which saved me an unknown +amount of work and grief. +Mark did the original implementation of the DBM version +of aliasing, installed the VFORK code, +wrote the current version of +.i rmail , +and was the person who really convinced me +to put the work into +.i delivermail +to turn it into +.i sendmail . +Kurt deserves accolades for using +.i sendmail +when I was myself afraid to take the risk; +how a person can continue to be so enthusiastic +in the face of so much bitter reality is beyond me. +.pp +Kurt, +Mark, +Kirk McKusick, +Marvin Solomon, +and many others have reviewed this paper, +giving considerable useful advice. +.pp +Special thanks are reserved for Mike Stonebraker at Berkeley +and Bob Epstein at Britton-Lee, +who both knowingly allowed me to put so much work into this +project +when there were so many other things I really should +have been working on. +.+c +.ce +REFERENCES +.nr ii 1.5i +.ip [Birrell82] +Birrell, A. D., +Levin, R., +Needham, R. M., +and +Schroeder, M. D., +.q "Grapevine: An Exercise in Distributed Computing." +In +.ul +Comm. A.C.M. 25, +4, +April 82. +.ip [Borden79] +Borden, S., +Gaines, R. S., +and +Shapiro, N. Z., +.ul +The MH Message Handling System: Users' Manual. +R-2367-PAF. +Rand Corporation. +October 1979. +.ip [Crocker77a] +Crocker, D. H., +Vittal, J. J., +Pogran, K. T., +and +Henderson, D. A. Jr., +.ul +Standard for the Format of ARPA Network Text Messages. +RFC 733, +NIC 41952. +In [Feinler78]. +November 1977. +.ip [Crocker77b] +Crocker, D. H., +.ul +Framework and Functions of the MS Personal Message System. +R-2134-ARPA, +Rand Corporation, +Santa Monica, California. +1977. +.ip [Crocker79] +Crocker, D. H., +Szurkowski, E. S., +and +Farber, D. J., +.ul +An Internetwork Memo Distribution Facility \*- MMDF. +6th Data Communication Symposium, +Asilomar. +November 1979. +.ip [Crocker82] +Crocker, D. H., +.ul +Standard for the Format of Arpa Internet Text Messages. +RFC 822. +Network Information Center, +SRI International, +Menlo Park, California. +August 1982. +.ip [Metcalfe76] +Metcalfe, R., +and +Boggs, D., +.q "Ethernet: Distributed Packet Switching for Local Computer Networks" , +.ul +Communications of the ACM 19, +7. +July 1976. +.ip [Feinler78] +Feinler, E., +and +Postel, J. +(eds.), +.ul +ARPANET Protocol Handbook. +NIC 7104, +Network Information Center, +SRI International, +Menlo Park, California. +1978. +.ip [NBS80] +National Bureau of Standards, +.ul +Specification of a Draft Message Format Standard. +Report No. ICST/CBOS 80-2. +October 1980. +.ip [Neigus73] +Neigus, N., +.ul +File Transfer Protocol for the ARPA Network. +RFC 542, NIC 17759. +In [Feinler78]. +August, 1973. +.ip [Nowitz78a] +Nowitz, D. A., +and +Lesk, M. E., +.ul +A Dial-Up Network of UNIX Systems. +Bell Laboratories. +In +UNIX Programmer's Manual, Seventh Edition, +Volume 2. +August, 1978. +.ip [Nowitz78b] +Nowitz, D. A., +.ul +Uucp Implementation Description. +Bell Laboratories. +In +UNIX Programmer's Manual, Seventh Edition, +Volume 2. +October, 1978. +.ip [Postel74] +Postel, J., +and +Neigus, N., +Revised FTP Reply Codes. +RFC 640, NIC 30843. +In [Feinler78]. +June, 1974. +.ip [Postel77] +Postel, J., +.ul +Mail Protocol. +NIC 29588. +In [Feinler78]. +November 1977. +.ip [Postel79a] +Postel, J., +.ul +Internet Message Protocol. +RFC 753, +IEN 85. +Network Information Center, +SRI International, +Menlo Park, California. +March 1979. +.ip [Postel79b] +Postel, J. B., +.ul +An Internetwork Message Structure. +In +.ul +Proceedings of the Sixth Data Communications Symposium, +IEEE. +New York. +November 1979. +.ip [Postel80] +Postel, J. B., +.ul +A Structured Format for Transmission of Multi-Media Documents. +RFC 767. +Network Information Center, +SRI International, +Menlo Park, California. +August 1980. +.ip [Postel82] +Postel, J. B., +.ul +Simple Mail Transfer Protocol. +RFC821 +(obsoleting RFC788). +Network Information Center, +SRI International, +Menlo Park, California. +August 1982. +.ip [Schmidt79] +Schmidt, E., +.ul +An Introduction to the Berkeley Network. +University of California, Berkeley California. +1979. +.ip [Shoens79] +Shoens, K., +.ul +Mail Reference Manual. +University of California, Berkeley. +In UNIX Programmer's Manual, +Seventh Edition, +Volume 2C. +December 1979. +.ip [Sluizer81] +Sluizer, S., +and +Postel, J. B., +.ul +Mail Transfer Protocol. +RFC 780. +Network Information Center, +SRI International, +Menlo Park, California. +May 1981. +.ip [Solomon81] +Solomon, M., Landweber, L., and Neuhengen, D., +.q "The Design of the CSNET Name Server." +CS-DN-2, +University of Wisconsin, Madison. +November 1981. +.ip [Su82] +Su, Zaw-Sing, +and +Postel, Jon, +.ul +The Domain Naming Convention for Internet User Applications. +RFC819. +Network Information Center, +SRI International, +Menlo Park, California. +August 1982. +.ip [UNIX83] +.ul +The UNIX Programmer's Manual, Seventh Edition, +Virtual VAX-11 Version, +Volume 1. +Bell Laboratories, +modified by the University of California, +Berkeley, California. +March, 1983. diff --git a/doc/intro/intro.ps b/doc/intro/intro.ps new file mode 100644 index 0000000..57c4216 --- /dev/null +++ b/doc/intro/intro.ps @@ -0,0 +1,1295 @@ +%!PS-Adobe-3.0 +%%Creator: groff version 1.08 +%%DocumentNeededResources: font Times-Roman +%%+ font Times-Italic +%%+ font 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Ho)-.92 F(we)-.25 E +-.15(ve)-.25 G 4.755 -.4(r, t).15 H 1.455(he general case is e).4 F 1.455 +(xtremely comple)-.15 F 3.955(x. F)-.15 F(or)-.15 E -.15(ex)72 516.6 S .192 +(ample, some netw).15 F .192(orks require point-to-point routing, which simpli\ +\214es the database update problem since)-.1 F .618(only adjacent hosts must b\ +e entered into the system tables, while others use end-to-end addressing.)72 +528.6 R(Some)5.618 E(netw)72 540.6 Q .123(orks use a left-associati)-.1 F .423 +-.15(ve s)-.25 H .123(yntax and others use a right-associati).15 F .423 -.15 +(ve s)-.25 H .123(yntax, causing ambiguity in mix).15 F(ed)-.15 E(addresses.)72 +552.6 Q .678(Internet standards seek to eliminate these problems.)97 568.8 R +(Initially)5.678 E 3.178(,t)-.65 G .679(hese proposed e)353.134 568.8 R .679 +(xpanding the address)-.15 F .65(pairs to address triples, consisting of {netw) +72 580.8 R .649(ork, host, resource} triples.)-.1 F(Netw)5.649 E .649 +(ork numbers must be uni)-.1 F -.15(ve)-.25 G -.2(r-).15 G 1.452 +(sally agreed upon, and hosts can be assigned locally on each netw)72 592.8 R +3.952(ork. The)-.1 F(user)3.952 E(-le)-.2 E -.15(ve)-.25 G 3.952(lp).15 G 1.452 +(resentation w)440.718 592.8 R(as)-.1 E 2.352(quickly e)72 604.8 R 2.352(xpand\ +ed to address domains, comprised of a local resource identi\214cation and a hi\ +erarchical)-.15 F .256(domain speci\214cation with a common static root.)72 +616.8 R .257(The domain technique separates the issue of ph)5.257 F .257 +(ysical v)-.05 F(er)-.15 E(-)-.2 E .807(sus logical addressing.)72 628.8 R -.15 +(Fo)5.807 G 3.307(re).15 G .807 +(xample, an address of the form \231eric@a.cc.berk)191.028 628.8 R(ele)-.1 E +-.65(y.)-.15 G .807(arpa\232 describes only the).65 F(logical or)72 640.8 Q +-.05(ga)-.18 G(nization of the address space.).05 E F2(Sendmail)97 657 Q F1 +.493(is intended to help bridge the g)2.992 F .493(ap between the totally)-.05 +F F2 .493(ad hoc)2.993 F F1 -.1(wo)2.993 G .493(rld of netw).1 F .493 +(orks that kno)-.1 F(w)-.25 E .855 +(nothing of each other and the clean, tightly-coupled w)72 669 R .854 +(orld of unique netw)-.1 F .854(ork numbers.)-.1 F .854(It can accept old)5.854 +F .32 LW 76 678.6 72 678.6 DL 80 678.6 76 678.6 DL 84 678.6 80 678.6 DL 88 +678.6 84 678.6 DL 92 678.6 88 678.6 DL 96 678.6 92 678.6 DL 100 678.6 96 678.6 +DL 104 678.6 100 678.6 DL 108 678.6 104 678.6 DL 112 678.6 108 678.6 DL 116 +678.6 112 678.6 DL 120 678.6 116 678.6 DL 124 678.6 120 678.6 DL 128 678.6 124 +678.6 DL 132 678.6 128 678.6 DL 136 678.6 132 678.6 DL 140 678.6 136 678.6 DL +144 678.6 140 678.6 DL 148 678.6 144 678.6 DL 152 678.6 148 678.6 DL 156 678.6 +152 678.6 DL 160 678.6 156 678.6 DL 164 678.6 160 678.6 DL 168 678.6 164 678.6 +DL 172 678.6 168 678.6 DL 176 678.6 172 678.6 DL 180 678.6 176 678.6 DL 184 +678.6 180 678.6 DL 188 678.6 184 678.6 DL 192 678.6 188 678.6 DL 196 678.6 192 +678.6 DL 200 678.6 196 678.6 DL 204 678.6 200 678.6 DL 208 678.6 204 678.6 DL +212 678.6 208 678.6 DL 216 678.6 212 678.6 DL/F3 8/Times-Roman@0 SF .557 +(*A considerable part of this w)93.6 690.6 R .557(ork w)-.08 F .557 +(as done while under the emplo)-.08 F 2.557(yo)-.08 G 2.556(ft)323.116 690.6 S +.556(he INGRES Project at the Uni)330.56 690.6 R -.12(ve)-.2 G .556 +(rsity of California at).12 F(Berk)72 700.2 Q(ele)-.08 E 2(ya)-.12 G +(nd at Britton Lee.)106.232 700.2 Q/F4 10/Times-Bold@0 SF +(SENDMAIL \212 An Inter)72 756 Q(netw)-.15 E(ork Mail Router)-.1 E(SMM:9-1) +462.9 756 Q EP +%%Page: 2 2 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF 192.28(SMM:9-2 SENDMAIL)72 60 R 2.5<8a41>2.5 G 2.5(nI) +383.99 60 S(nter)395.94 60 Q(netw)-.15 E(ork Mail Router)-.1 E/F1 10 +/Times-Roman@0 SF .632(arbitrary address syntax)72 96 R .633(es, resolving amb\ +iguities using heuristics speci\214ed by the system administrator)-.15 F 3.133 +(,a)-.4 G(s)500.11 96 Q .348(well as domain-based addressing.)72 108 R .347 +(It helps guide the con)5.347 F -.15(ve)-.4 G .347 +(rsion of message formats between disparate net-).15 F -.1(wo)72 120 S 3.394 +(rks. In).1 F(short,)3.394 E/F2 10/Times-Italic@0 SF(sendmail)3.394 E F1 .894 +(is designed to assist a graceful transition to consistent internetw)3.394 F +.895(ork addressing)-.1 F(schemes.)72 132 Q .153 +(Section 1 discusses the design goals for)97 160.2 R F2(sendmail)2.653 E F1 +5.153(.S)C .152(ection 2 gi)308.214 160.2 R -.15(ve)-.25 G 2.652(sa).15 G 2.652 +(no)370.76 160.2 S -.15(ve)383.262 160.2 S(rvie).15 E 2.652(wo)-.25 G 2.652(ft) +422.724 160.2 S .152(he basic functions)431.486 160.2 R .644(of the system.)72 +172.2 R .644(In section 3, details of usage are discussed.)5.644 F .644 +(Section 4 compares)5.644 F F2(sendmail)3.144 E F1 .645(to other internet)3.144 +F(mail routers, and an e)72 184.2 Q -.25(va)-.25 G(luation of).25 E F2 +(sendmail)2.5 E F1(is gi)2.5 E -.15(ve)-.25 G 2.5(ni).15 G 2.5(ns)283.3 184.2 S +(ection 5, including future plans.)294.69 184.2 Q F0 2.5(1. DESIGN)72 208.2 R +(GO)2.5 E(ALS)-.4 E F1(Design goals for)112 224.4 Q F2(sendmail)2.5 E F1 +(include:)2.5 E 12.5(\(1\) Compatibility)92 240.6 R 1.363(with the e)3.864 F +1.363(xisting mail programs, including Bell v)-.15 F 1.363 +(ersion 6 mail, Bell v)-.15 F 1.363(ersion 7)-.15 F 1.202(mail [UNIX83], Berk) +118.66 252.6 R(ele)-.1 E(y)-.15 E F2(Mail)3.702 E F1 1.202 +([Shoens79], BerkNet mail [Schmidt79], and hopefully UUCP)3.702 F(mail [No) +118.66 264.6 Q(witz78a, No)-.25 E 2.5(witz78b]. ARP)-.25 F(ANET mail [Crock) +-.92 E(er77a, Postel77] w)-.1 E(as also required.)-.1 E 12.5(\(2\) Reliability) +92 280.8 R 4.003(,i)-.65 G 4.003(nt)169.523 280.8 S 1.502 +(he sense of guaranteeing that e)181.306 280.8 R -.15(ve)-.25 G 1.502 +(ry message is correctly deli).15 F -.15(ve)-.25 G 1.502(red or at least).15 F +.368 +(brought to the attention of a human for correct disposal; no message should e) +118.66 292.8 R -.15(ve)-.25 G 2.868(rb).15 G 2.868(ec)452.252 292.8 S +(ompletely)464 292.8 Q 2.541(lost. This)118.66 304.8 R .041(goal w)2.541 F .041 +(as considered essential because of the emphasis on mail in our en)-.1 F 2.54 +(vironment. It)-.4 F 1.754 +(has turned out to be one of the hardest goals to satisfy)118.66 316.8 R 4.255 +(,e)-.65 G 1.755(specially in the f)363.75 316.8 R 1.755(ace of the man)-.1 F +(y)-.15 E .978(anomalous message formats produced by v)118.66 328.8 R .977 +(arious ARP)-.25 F .977(ANET sites.)-.92 F -.15(Fo)5.977 G 3.477(re).15 G .977 +(xample, certain sites)420.116 328.8 R .069 +(generate improperly formated addresses, occasionally causing error)118.66 +340.8 R .069(-message loops.)-.2 F .069(Some hosts)5.069 F .063(use blanks in \ +names, causing problems with UNIX mail programs that assume that an address is) +118.66 352.8 R .111(one w)118.66 364.8 R 2.611(ord. The)-.1 F .111 +(semantics of some \214elds are interpreted slightly dif)2.611 F .112 +(ferently by dif)-.25 F .112(ferent sites.)-.25 F(In)5.112 E(summary)118.66 +376.8 Q 3.023(,t)-.65 G .523(he obscure features of the ARP)163.533 376.8 R +.523(ANET mail protocol really)-.92 F F2(ar)3.023 E(e)-.37 E F1 .522 +(used and are dif)3.023 F(\214cult)-.25 E(to support, b)118.66 388.8 Q +(ut must be supported.)-.2 E 12.5(\(3\) Existing)92 405 R(softw)2.938 E .438 +(are to do actual deli)-.1 F -.15(ve)-.25 G .439(ry should be used whene).15 F +-.15(ve)-.25 G 2.939(rp).15 G 2.939(ossible. This)387.654 405 R .439(goal deri) +2.939 F -.15(ve)-.25 G 2.939(sa).15 G(s)500.11 405 Q +(much from political and practical considerations as technical.)118.66 417 Q +12.5(\(4\) Easy)92 433.2 R -.15(ex)2.899 G .399(pansion to f).15 F .399 +(airly comple)-.1 F 2.898(xe)-.15 G -.4(nv)261.064 433.2 S .398 +(ironments, including multiple connections to a single net-).4 F -.1(wo)118.66 +445.2 S .115 +(rk type \(such as with multiple UUCP or Ether nets [Metcalfe76]\).).1 F .115 +(This goal requires consid-)5.115 F .587(eration of the contents of an address\ + as well as its syntax in order to determine which g)118.66 457.2 R(ate)-.05 E +-.1(wa)-.25 G(y).1 E 1.018(to use.)118.66 469.2 R -.15(Fo)6.018 G 3.518(re).15 +G 1.018(xample, the ARP)173.354 469.2 R 1.019 +(ANET is bringing up the TCP protocol to replace the old NCP)-.92 F 4.791 +(protocol. No)118.66 481.2 R 2.291(host at Berk)4.791 F(ele)-.1 E 4.791(yr)-.15 +G 2.291(uns both TCP and NCP)256.235 481.2 R 4.791(,s)-1.11 G 4.79(oi)369.37 +481.2 S 4.79(ti)381.94 481.2 S 4.79(sn)392.29 481.2 S 2.29 +(ecessary to look at the)405.97 481.2 R(ARP)118.66 493.2 Q .016 +(ANET host name to determine whether to route mail to an NCP g)-.92 F(ate)-.05 +E -.1(wa)-.25 G 2.517(yo).1 G 2.517(raT)435.569 493.2 S .017(CP g)454.483 493.2 +R(ate)-.05 E -.1(wa)-.25 G -.65(y.).1 G 12.5(\(5\) Con\214guration)92 509.4 R +.145(should not be compiled into the code.)2.645 F 2.645(As)5.145 G .145 +(ingle compiled program should be able)346.905 509.4 R .91(to run as is at an) +118.66 521.4 R 3.41(ys)-.15 G .91 +(ite \(barring such basic changes as the CPU type or the operating system\).) +200.63 521.4 R 2.61 -.8(We h)118.66 533.4 T -2.25 -.2(av e).8 H 1.009 +(found this seemingly unimportant goal to be critical in real life.)3.71 F +1.009(Besides the simple)6.009 F .66(problems that occur when an)118.66 545.4 R +3.16(yp)-.15 G .66(rogram gets recompiled in a dif)249.84 545.4 R .66 +(ferent en)-.25 F .66(vironment, man)-.4 F 3.16(ys)-.15 G(ites)490.11 545.4 Q +(lik)118.66 557.4 Q 2.5(et)-.1 G 2.5<6f99>138.84 557.4 S(\214ddle\232 with an) +150.78 557.4 Q(ything that the)-.15 E 2.5(yw)-.15 G(ill be recompiling an) +282.42 557.4 Q(yw)-.15 E(ay)-.1 E(.)-.65 E(\(6\))92 573.6 Q F2(Sendmail)118.66 +573.6 Q F1 .184(must be able to let v)2.684 F .184 +(arious groups maintain their o)-.25 F .184(wn mailing lists, and let indi)-.25 +F(viduals)-.25 E(specify their o)118.66 585.6 Q(wn forw)-.25 E +(arding, without modifying the system alias \214le.)-.1 E 12.5(\(7\) Each)92 +601.8 R .313(user should be able to specify which mailer to e)2.813 F -.15(xe) +-.15 G .313(cute to process mail being deli).15 F -.15(ve)-.25 G .314(red for) +.15 F 3.098(him. This)118.66 613.8 R .598(feature allo)3.098 F .598 +(ws users who are using specialized mailers that use a dif)-.25 F .598 +(ferent format to)-.25 F -.2(bu)118.66 625.8 S .25(ild their en).2 F .25 +(vironment without changing the system, and f)-.4 F .25 +(acilitates specialized functions \(such)-.1 F(as returning an \231I am on v) +118.66 637.8 Q(acation\232 message\).)-.25 E 12.5(\(8\) Netw)92 654 R 1.553 +(ork traf)-.1 F 1.552(\214c should be minimized by batching addresses to a sin\ +gle host where possible,)-.25 F(without assistance from the user)118.66 666 Q +(.)-.55 E .374(These goals moti)112 682.2 R -.25(va)-.25 G .374 +(ted the architecture illustrated in \214gure 1.).25 F .375 +(The user interacts with a mail gen-)5.375 F .491(erating and sending program.) +87 694.2 R .491(When the mail is created, the generator calls)5.491 F F2 +(sendmail)2.99 E F1 2.99(,w)C .49(hich routes the)444.14 694.2 R .84 +(message to the correct mailer\(s\).)87 706.2 R .841 +(Since some of the senders may be netw)5.84 F .841(ork serv)-.1 F .841 +(ers and some of the)-.15 F(mailers may be netw)87 718.2 Q(ork clients,)-.1 E +F2(sendmail)2.5 E F1(may be used as an internet mail g)2.5 E(ate)-.05 E -.1(wa) +-.25 G -.65(y.).1 G EP +%%Page: 3 3 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF(SENDMAIL \212 An Inter)72 60 Q(netw)-.15 E +(ork Mail Router)-.1 E(SMM:9-3)462.9 60 Q .4 LW 77 108 72 108 DL 79 108 74 108 +DL 84 108 79 108 DL 89 108 84 108 DL 94 108 89 108 DL 99 108 94 108 DL 104 108 +99 108 DL 109 108 104 108 DL 114 108 109 108 DL 119 108 114 108 DL 124 108 119 +108 DL 129 108 124 108 DL 134 108 129 108 DL 139 108 134 108 DL 144 108 139 108 +DL 149 108 144 108 DL 154 108 149 108 DL 159 108 154 108 DL 164 108 159 108 DL +169 108 164 108 DL 174 108 169 108 DL 179 108 174 108 DL 184 108 179 108 DL 189 +108 184 108 DL 194 108 189 108 DL 199 108 194 108 DL 204 108 199 108 DL 209 108 +204 108 DL 214 108 209 108 DL 219 108 214 108 DL 224 108 219 108 DL 229 108 224 +108 DL 234 108 229 108 DL 239 108 234 108 DL 244 108 239 108 DL 249 108 244 108 +DL 254 108 249 108 DL 259 108 254 108 DL 264 108 259 108 DL 269 108 264 108 DL +274 108 269 108 DL 279 108 274 108 DL 284 108 279 108 DL 289 108 284 108 DL 294 +108 289 108 DL 299 108 294 108 DL 304 108 299 108 DL 309 108 304 108 DL 314 108 +309 108 DL 319 108 314 108 DL 324 108 319 108 DL 329 108 324 108 DL 334 108 329 +108 DL 339 108 334 108 DL 344 108 339 108 DL 349 108 344 108 DL 354 108 349 108 +DL 359 108 354 108 DL 364 108 359 108 DL 369 108 364 108 DL 374 108 369 108 DL +379 108 374 108 DL 384 108 379 108 DL 389 108 384 108 DL 394 108 389 108 DL 399 +108 394 108 DL 404 108 399 108 DL 409 108 404 108 DL 414 108 409 108 DL 419 108 +414 108 DL 424 108 419 108 DL 429 108 424 108 DL 434 108 429 108 DL 439 108 434 +108 DL 444 108 439 108 DL 449 108 444 108 DL 454 108 449 108 DL 459 108 454 108 +DL 464 108 459 108 DL 469 108 464 108 DL 474 108 469 108 DL 479 108 474 108 DL +484 108 479 108 DL 489 108 484 108 DL 494 108 489 108 DL 499 108 494 108 DL 504 +108 499 108 DL/F1 10/Times-Roman@0 SF(sender1)164.45 155.6 Q 144 135.6 144 +171.6 DL 216 135.6 144 135.6 DL 216 171.6 216 135.6 DL 144 171.6 216 171.6 DL +(sender2)272.45 155.6 Q 252 135.6 252 171.6 DL 324 135.6 252 135.6 DL 324 171.6 +324 135.6 DL 252 171.6 324 171.6 DL(sender3)380.45 155.6 Q 360 135.6 360 171.6 +DL 432 135.6 360 135.6 DL 432 171.6 432 135.6 DL 360 171.6 432 171.6 DL 288 +207.6 288 171.6 DL 288 207.6 286.2 200.4 DL 288 207.6 289.8 200.4 DL(sendmail) +269.945 227.6 Q 216 207.6 216 243.6 DL 360 207.6 216 207.6 DL 360 243.6 360 +207.6 DL 216 243.6 360 243.6 DL 288 279.6 288 243.6 DL 288 279.6 286.2 272.4 DL +288 279.6 289.8 272.4 DL(mailer1)164.725 299.6 Q 144 279.6 144 315.6 DL 216 +279.6 144 279.6 DL 216 315.6 216 279.6 DL 144 315.6 216 315.6 DL(mailer2) +272.725 299.6 Q 252 279.6 252 315.6 DL 324 279.6 252 279.6 DL 324 315.6 324 +279.6 DL 252 315.6 324 315.6 DL(mailer3)380.725 299.6 Q 360 279.6 360 315.6 DL +432 279.6 360 279.6 DL 432 315.6 432 279.6 DL 360 315.6 432 315.6 DL 252 207.6 +180 171.6 DL 252 207.6 244.728 206.016 DL 252 207.6 246.384 202.776 DL 324 +207.6 396 171.6 DL 324 207.6 329.616 202.776 DL 324 207.6 331.272 206.016 DL +180 279.6 252 243.6 DL 180 279.6 185.616 274.776 DL 180 279.6 187.272 278.016 +DL 396 279.6 324 243.6 DL 396 279.6 388.728 278.016 DL 396 279.6 390.384 +274.776 DL(Figure 1 \212 Sendmail System Structure.)208 346.8 Q 77 358.8 72 +358.8 DL 79 358.8 74 358.8 DL 84 358.8 79 358.8 DL 89 358.8 84 358.8 DL 94 +358.8 89 358.8 DL 99 358.8 94 358.8 DL 104 358.8 99 358.8 DL 109 358.8 104 +358.8 DL 114 358.8 109 358.8 DL 119 358.8 114 358.8 DL 124 358.8 119 358.8 DL +129 358.8 124 358.8 DL 134 358.8 129 358.8 DL 139 358.8 134 358.8 DL 144 358.8 +139 358.8 DL 149 358.8 144 358.8 DL 154 358.8 149 358.8 DL 159 358.8 154 358.8 +DL 164 358.8 159 358.8 DL 169 358.8 164 358.8 DL 174 358.8 169 358.8 DL 179 +358.8 174 358.8 DL 184 358.8 179 358.8 DL 189 358.8 184 358.8 DL 194 358.8 189 +358.8 DL 199 358.8 194 358.8 DL 204 358.8 199 358.8 DL 209 358.8 204 358.8 DL +214 358.8 209 358.8 DL 219 358.8 214 358.8 DL 224 358.8 219 358.8 DL 229 358.8 +224 358.8 DL 234 358.8 229 358.8 DL 239 358.8 234 358.8 DL 244 358.8 239 358.8 +DL 249 358.8 244 358.8 DL 254 358.8 249 358.8 DL 259 358.8 254 358.8 DL 264 +358.8 259 358.8 DL 269 358.8 264 358.8 DL 274 358.8 269 358.8 DL 279 358.8 274 +358.8 DL 284 358.8 279 358.8 DL 289 358.8 284 358.8 DL 294 358.8 289 358.8 DL +299 358.8 294 358.8 DL 304 358.8 299 358.8 DL 309 358.8 304 358.8 DL 314 358.8 +309 358.8 DL 319 358.8 314 358.8 DL 324 358.8 319 358.8 DL 329 358.8 324 358.8 +DL 334 358.8 329 358.8 DL 339 358.8 334 358.8 DL 344 358.8 339 358.8 DL 349 +358.8 344 358.8 DL 354 358.8 349 358.8 DL 359 358.8 354 358.8 DL 364 358.8 359 +358.8 DL 369 358.8 364 358.8 DL 374 358.8 369 358.8 DL 379 358.8 374 358.8 DL +384 358.8 379 358.8 DL 389 358.8 384 358.8 DL 394 358.8 389 358.8 DL 399 358.8 +394 358.8 DL 404 358.8 399 358.8 DL 409 358.8 404 358.8 DL 414 358.8 409 358.8 +DL 419 358.8 414 358.8 DL 424 358.8 419 358.8 DL 429 358.8 424 358.8 DL 434 +358.8 429 358.8 DL 439 358.8 434 358.8 DL 444 358.8 439 358.8 DL 449 358.8 444 +358.8 DL 454 358.8 449 358.8 DL 459 358.8 454 358.8 DL 464 358.8 459 358.8 DL +469 358.8 464 358.8 DL 474 358.8 469 358.8 DL 479 358.8 474 358.8 DL 484 358.8 +479 358.8 DL 489 358.8 484 358.8 DL 494 358.8 489 358.8 DL 499 358.8 494 358.8 +DL 504 358.8 499 358.8 DL F0 2.5(2. O)72 394.8 R(VER)-.5 E(VIEW)-.55 E 2.5 +(2.1. System)87 418.8 R(Or)2.5 E(ganization)-.1 E/F2 10/Times-Italic@0 SF +(Sendmail)127 435 Q F1 .874(neither interf)3.374 F .874 +(aces with the user nor does actual mail deli)-.1 F -.15(ve)-.25 G(ry).15 E +5.873(.R)-.65 G(ather)431.241 435 Q 3.373(,i)-.4 G 3.373(tc)459.484 435 S .873 +(ollects a)470.077 435 R .619(message generated by a user interf)102 447 R .619 +(ace program \(UIP\) such as Berk)-.1 F(ele)-.1 E(y)-.15 E F2(Mail)3.12 E F1 +3.12(,M)C 3.12(S[)427.6 447 S(Crock)439.61 447 Q .62(er77b], or)-.1 F 1.428 +(MH [Borden79], edits the message as required by the destination netw)102 459 R +1.427(ork, and calls appropriate)-.1 F .28(mailers to do mail deli)102 473 R +-.15(ve)-.25 G .281(ry or queueing for netw).15 F .281(ork transmission)-.1 F +/F3 7/Times-Roman@0 SF(1)364.275 469 Q F1 5.281(.T)367.775 473 S .281 +(his discipline allo)381.666 473 R .281(ws the inser)-.25 F(-)-.2 E 1.354 +(tion of ne)102 485 R 3.854(wm)-.25 G 1.354(ailers at minimum cost.)161.642 485 +R 1.354(In this sense)6.354 F F2(sendmail)3.853 E F1 1.353 +(resembles the Message Processing)3.853 F(Module \(MPM\) of [Postel79b].)102 +497 Q F0 2.5(2.2. Interfaces)87 521 R(to the Outside W)2.5 E(orld)-.75 E F1 +.041(There are three w)127 537.2 R(ays)-.1 E F2(sendmail)2.541 E F1 .041 +(can communicate with the outside w)2.541 F .042(orld, both in recei)-.1 F .042 +(ving and)-.25 F 1.195(in sending mail.)102 549.2 R 1.194 +(These are using the con)6.194 F -.15(ve)-.4 G 1.194(ntional UNIX ar).15 F +1.194(gument v)-.18 F 1.194(ector/return status, speaking)-.15 F(SMTP o)102 +561.2 Q -.15(ve)-.15 G 2.5(rap).15 G(air of UNIX pipes, and speaking SMTP o) +162.53 561.2 Q -.15(ve)-.15 G 2.5(ra).15 G 2.5(ni)348.03 561.2 S +(nterprocess\(or\) channel.)358.31 561.2 Q F0 2.5(2.2.1. Ar)102 585.2 R +(gument v)-.1 E(ector/exit status)-.1 E F1 .52(This technique is the standard \ +UNIX method for communicating with the process.)142 601.4 R 3.02(Al)5.52 G(ist) +494.55 601.4 Q .442(of recipients is sent in the ar)117 613.4 R .441(gument v) +-.18 F(ector)-.15 E 2.941(,a)-.4 G .441 +(nd the message body is sent on the standard input.)299.491 613.4 R(An)117 +625.4 Q .351(ything that the mailer prints is simply collected and sent back t\ +o the sender if there were an)-.15 F(y)-.15 E 2.621(problems. The)117 637.4 R +-.15(ex)2.621 G .121(it status from the mailer is collected after the message \ +is sent, and a diagnostic).15 F(is printed if appropriate.)117 649.4 Q .32 LW +76 678.8 72 678.8 DL 80 678.8 76 678.8 DL 84 678.8 80 678.8 DL 88 678.8 84 +678.8 DL 92 678.8 88 678.8 DL 96 678.8 92 678.8 DL 100 678.8 96 678.8 DL 104 +678.8 100 678.8 DL 108 678.8 104 678.8 DL 112 678.8 108 678.8 DL 116 678.8 112 +678.8 DL 120 678.8 116 678.8 DL 124 678.8 120 678.8 DL 128 678.8 124 678.8 DL +132 678.8 128 678.8 DL 136 678.8 132 678.8 DL 140 678.8 136 678.8 DL 144 678.8 +140 678.8 DL 148 678.8 144 678.8 DL 152 678.8 148 678.8 DL 156 678.8 152 678.8 +DL 160 678.8 156 678.8 DL 164 678.8 160 678.8 DL 168 678.8 164 678.8 DL 172 +678.8 168 678.8 DL 176 678.8 172 678.8 DL 180 678.8 176 678.8 DL 184 678.8 180 +678.8 DL 188 678.8 184 678.8 DL 192 678.8 188 678.8 DL 196 678.8 192 678.8 DL +200 678.8 196 678.8 DL 204 678.8 200 678.8 DL 208 678.8 204 678.8 DL 212 678.8 +208 678.8 DL 216 678.8 212 678.8 DL/F4 5/Times-Roman@0 SF(1)93.6 689.2 Q/F5 8 +/Times-Roman@0 SF -.12(ex)3.2 K(cept when mailing to a \214le, when).12 E/F6 8 +/Times-Italic@0 SF(sendmail)2 E F5(does the deli)2 E -.12(ve)-.2 G(ry directly) +.12 E(.)-.52 E EP +%%Page: 4 4 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF 192.28(SMM:9-4 SENDMAIL)72 60 R 2.5<8a41>2.5 G 2.5(nI) +383.99 60 S(nter)395.94 60 Q(netw)-.15 E(ork Mail Router)-.1 E 2.5(2.2.2. SMTP) +102 96 R -.1(ove)2.5 G 2.5(rp).1 G(ipes)186.52 96 Q/F1 10/Times-Roman@0 SF .774 +(The SMTP protocol [Postel82] can be used to run an interacti)142 112.2 R 1.074 +-.15(ve l)-.25 H .774(ock-step interf).15 F .774(ace with)-.1 F .507 +(the mailer)117 124.2 R 5.507(.A)-.55 G .506(subprocess is still created, b) +175.461 124.2 R .506(ut no recipient addresses are passed to the mailer via)-.2 +F .075(the ar)117 136.2 R .075(gument list.)-.18 F .075(Instead, the)5.075 F +2.575(ya)-.15 G .075 +(re passed one at a time in commands sent to the processes stan-)249.805 136.2 +R .19(dard input.)117 148.2 R(An)5.19 E .19(ything appearing on the standard o\ +utput must be a reply code in a special format.)-.15 F F0 2.5(2.2.3. SMTP)102 +172.2 R -.1(ove)2.5 G 2.5(ra).1 G 2.5(nI)185.96 172.2 S(PC connection)197.91 +172.2 Q F1 .366(This technique is similar to the pre)142 188.4 R .366 +(vious technique, e)-.25 F .366(xcept that it uses a 4.2bsd IPC chan-)-.15 F +.953(nel [UNIX83].)117 200.4 R .953(This method is e)5.953 F .953 +(xceptionally \215e)-.15 F .952 +(xible in that the mailer need not reside on the)-.15 F(same machine.)117 212.4 +Q(It is normally used to connect to a sendmail process on another machine.)5 E +F0 2.5(2.3. Operational)87 236.4 R(Description)2.5 E F1 .228(When a sender w) +127 252.6 R .228(ants to send a message, it issues a request to)-.1 F/F2 10 +/Times-Italic@0 SF(sendmail)2.729 E F1 .229(using one of the three)2.729 F +1.028(methods described abo)102 264.6 R -.15(ve)-.15 G(.).15 E F2(Sendmail) +6.028 E F1 1.028(operates in tw)3.528 F 3.528(od)-.1 G 1.028(istinct phases.) +325.706 264.6 R 1.028(In the \214rst phase, it collects)6.028 F .612 +(and stores the message.)102 276.6 R .612(In the second phase, message deli) +5.612 F -.15(ve)-.25 G .612(ry occurs.).15 F .612(If there were errors during) +5.612 F 1.59(processing during the second phase,)102 288.6 R F2(sendmail)4.09 E +F1 1.59(creates and returns a ne)4.09 F 4.09(wm)-.25 G 1.59 +(essage describing the)415.84 288.6 R +(error and/or returns an status code telling what went wrong.)102 300.6 Q F0 +2.5(2.3.1. Ar)102 324.6 R(gument pr)-.1 E(ocessing and addr)-.18 E(ess parsing) +-.18 E F1(If)142 340.8 Q F2(sendmail)3.321 E F1 .821 +(is called using one of the tw)3.321 F 3.322(os)-.1 G .822 +(ubprocess techniques, the ar)320.66 340.8 R .822(guments are \214rst)-.18 F +.797(scanned and option speci\214cations are processed.)117 352.8 R .796 +(Recipient addresses are then collected, either)5.796 F .717(from the command \ +line or from the SMTP RCPT command, and a list of recipients is created.)117 +364.8 R .347(Aliases are e)117 376.8 R .347 +(xpanded at this step, including mailing lists.)-.15 F .347(As much v)5.347 F +.346(alidation as possible of the)-.25 F 1.001 +(addresses is done at this step: syntax is check)117 388.8 R 1.002 +(ed, and local addresses are v)-.1 F 1.002(eri\214ed, b)-.15 F 1.002 +(ut detailed)-.2 F .709 +(checking of host names and addresses is deferred until deli)117 400.8 R -.15 +(ve)-.25 G(ry).15 E 5.708(.F)-.65 G(orw)388.946 400.8 Q .708 +(arding is also performed)-.1 F(as the local addresses are v)117 412.8 Q +(eri\214ed.)-.15 E F2(Sendmail)142 429 Q F1 .307 +(appends each address to the recipient list after parsing.)2.807 F .307 +(When a name is aliased)5.307 F .322(or forw)117 441 R .322(arded, the old nam\ +e is retained in the list, and a \215ag is set that tells the deli)-.1 F -.15 +(ve)-.25 G .322(ry phase to).15 F .479(ignore this recipient.)117 453 R .479 +(This list is k)5.479 F .479(ept free from duplicates, pre)-.1 F -.15(ve)-.25 G +.48(nting alias loops and duplicate).15 F(messages deli)117 465 Q -.15(ve)-.25 +G(rd to the same recipient, as might occur if a person is in tw).15 E 2.5(og) +-.1 G(roups.)428.12 465 Q F0 2.5(2.3.2. Message)102 489 R(collection)2.5 E F2 +(Sendmail)142 505.2 Q F1 .454(then collects the message.)2.954 F .454 +(The message should ha)5.454 F .754 -.15(ve a h)-.2 H .453(eader at the be).15 +F(ginning.)-.15 E .778(No formatting requirements are imposed on the message e) +117 517.2 R .778(xcept that the)-.15 F 3.278(ym)-.15 G .778(ust be lines of te) +427.708 517.2 R(xt)-.15 E .78(\(i.e., binary data is not allo)117 529.2 R 3.28 +(wed\). The)-.25 F .779(header is parsed and stored in memory)3.28 F 3.279(,a) +-.65 G .779(nd the body of)443.613 529.2 R(the message is sa)117 541.2 Q -.15 +(ve)-.2 G 2.5(di).15 G 2.5(nat)204.97 541.2 S(emporary \214le.)222.19 541.2 Q +3.227 -.8(To s)142 557.4 T 1.627(implify the program interf).8 F 1.628 +(ace, the message is collected e)-.1 F -.15(ve)-.25 G 4.128(ni).15 G 4.128(fn) +420.536 557.4 S 4.128(oa)432.994 557.4 S 1.628(ddresses were)446.562 557.4 R +-.25(va)117 569.4 S 2.5(lid. The).25 F(message will be returned with an error) +2.5 E(.)-.55 E F0 2.5(2.3.3. Message)102 593.4 R(deli)2.5 E -.1(ve)-.1 G(ry).1 +E F1 -.15(Fo)142 609.6 S 2.618(re).15 G .117 +(ach unique mailer and host in the recipient list,)162.798 609.6 R F2(sendmail) +2.617 E F1 .117(calls the appropriate mailer)2.617 F(.)-.55 E .619 +(Each mailer in)117 621.6 R -.2(vo)-.4 G .619(cation sends to all users recei) +.2 F .619(ving the message on one host.)-.25 F .62(Mailers that only)5.62 F +(accept one recipient at a time are handled properly)117 633.6 Q(.)-.65 E .47 +(The message is sent to the mailer using one of the same three interf)142 649.8 +R .47(aces used to submit a)-.1 F 1.465(message to sendmail.)117 661.8 R 1.465 +(Each cop)6.465 F 3.965(yo)-.1 G 3.965(ft)263.925 661.8 S 1.465 +(he message is prepended by a customized header)274 661.8 R 6.465(.T)-.55 G(he) +494.56 661.8 Q 1.455(mailer status code is caught and check)117 673.8 R 1.455 +(ed, and a suitable error message gi)-.1 F -.15(ve)-.25 G 3.955(na).15 G 3.955 +(sa)448.115 673.8 S(ppropriate.)460.4 673.8 Q .589(The e)117 685.8 R .589(xit \ +code must conform to a system standard or a generic message \(\231Service una) +-.15 F -.25(va)-.2 G(ilable\232\)).25 E(is gi)117 697.8 Q -.15(ve)-.25 G(n.).15 +E EP +%%Page: 5 5 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF(SENDMAIL \212 An Inter)72 60 Q(netw)-.15 E +(ork Mail Router)-.1 E(SMM:9-5)462.9 60 Q 2.5(2.3.4. Queueing)102 96 R -.25(fo) +2.5 G 2.5(rr).25 G(etransmission)192.4 96 Q/F1 10/Times-Roman@0 SF .209(If the\ + mailer returned an status that indicated that it might be able to handle the \ +mail later)142 112.2 R(,)-.4 E/F2 10/Times-Italic@0 SF(sendmail)117 124.2 Q F1 +(will queue the mail and try ag)2.5 E(ain later)-.05 E(.)-.55 E F0 2.5 +(2.3.5. Retur)102 148.2 R 2.5(nt)-.15 G 2.5(os)165.73 148.2 S(ender)177.12 +148.2 Q F1 .588(If errors occur during processing,)142 164.4 R F2(sendmail) +3.088 E F1 .589(returns the message to the sender for retrans-)3.088 F 3.133 +(mission. The)117 176.4 R .632(letter can be mailed back or written in the \ +\214le \231dead.letter\232 in the sender')3.133 F 3.132(sh)-.55 G(ome)486.78 +176.4 Q(directory)117 190.4 Q/F3 7/Times-Roman@0 SF(2)153.1 186.4 Q F1(.)156.6 +190.4 Q F0 2.5(2.4. Message)87 214.4 R(Header Editing)2.5 E F1 1.756 +(Certain editing of the message header occurs automatically)127 230.6 R 6.756 +(.H)-.65 G 1.756(eader lines can be inserted)391.456 230.6 R .41 +(under control of the con\214guration \214le.)102 242.6 R .41 +(Some lines can be mer)5.41 F .41(ged; for e)-.18 F .41 +(xample, a \231From:\232 line and)-.15 F 2.5<6199>102 254.6 S +(Full-name:\232 line can be mer)113.38 254.6 Q +(ged under certain circumstances.)-.18 E F0 2.5(2.5. Con\214guration)87 278.6 R +(File)2.5 E F1 .798(Almost all con\214guration information is read at runtime \ +from an ASCII \214le, encoding macro)127 294.8 R .679 +(de\214nitions \(de\214ning the v)102 306.8 R .678 +(alue of macros used internally\), header declarations \(telling sendmail the) +-.25 F 1.009(format of header lines that it will process specially)102 318.8 R +3.509(,i)-.65 G 1.009(.e., lines that it will add or reformat\), mailer)320.398 +318.8 R .478(de\214nitions \(gi)102 330.8 R .478(ving information such as the \ +location and characteristics of each mailer\), and address)-.25 F(re)102 342.8 +Q .428(writing rules \(a limited production system to re)-.25 F .429 +(write addresses which is used to parse and re)-.25 F(write)-.25 E +(the addresses\).)102 354.8 Q 2.828 -.8(To i)127 371 T(mpro).8 E 1.528 -.15 +(ve p)-.15 H 1.228(erformance when reading the con\214guration \214le, a memor\ +y image can be pro-).15 F 2.5(vided. This)102 383 R(pro)2.5 E +(vides a \231compiled\232 form of the con\214guration \214le.)-.15 E F0 2.5 +(3. USA)72 407 R(GE AND IMPLEMENT)-.55 E -.95(AT)-.9 G(ION).95 E 2.5(3.1. Ar)87 +431 R(guments)-.1 E F1(Ar)127 447.2 Q .376 +(guments may be \215ags and addresses.)-.18 F .377(Flags set v)5.377 F .377 +(arious processing options.)-.25 F -.15(Fo)5.377 G(llo).15 E .377(wing \215ag) +-.25 F(ar)102 459.2 Q .281(guments, address ar)-.18 F .281(guments may be gi) +-.18 F -.15(ve)-.25 G .281(n, unless we are running in SMTP mode.).15 F .28 +(Addresses fol-)5.28 F(lo)102 471.2 Q 2.5(wt)-.25 G(he syntax in RFC822 [Crock) +122.03 471.2 Q(er82] for ARP)-.1 E(ANET address formats.)-.92 E +(In brief, the format is:)5 E 12.5(\(1\) An)107 487.4 R +(ything in parentheses is thro)-.15 E(wn a)-.25 E -.1(wa)-.15 G 2.5(y\().1 G +(as a comment\).)299.65 487.4 Q 12.5(\(2\) An)107 503.6 R .051 +(ything in angle brack)-.15 F .051(ets \(\231<)-.1 F .051 +(>\232\) is preferred o)1.666 F -.15(ve)-.15 G 2.551(ra).15 G -.15(ny)348.064 +503.6 S .051(thing else.).15 F .051(This rule implements the)5.051 F(ARP)133.66 +515.6 Q(ANET standard that addresses of the form)-.92 E +(user name <machine-address>)173.66 531.8 Q(will send to the electronic \231ma\ +chine-address\232 rather than the human \231user name.)133.66 548 Q<9a>-.7 E +12.5(\(3\) Double)107 564.2 R 2.246(quotes \()4.746 F -2.754 2.5("\) q)2.5 H +2.246(uote phrases; backslashes quote characters.)224.188 564.2 R 2.246 +(Backslashes are more)7.246 F(po)133.66 576.2 Q .654(werful in that the)-.25 F +3.154(yw)-.15 G .655(ill cause otherwise equi)229.196 576.2 R -.25(va)-.25 G +.655(lent phrases to compare dif).25 F .655(ferently \212 for)-.25 F -.15(ex) +133.66 588.2 S(ample,).15 E F2(user)2.5 E F1(and)2.5 E F2("user")2.5 E F1 +(are equi)2.5 E -.25(va)-.25 G(lent, b).25 E(ut)-.2 E F2(\\user)2.5 E F1 +(is dif)2.5 E(ferent from either of them.)-.25 E -.15(Pa)127 604.4 S 1.12 +(rentheses, angle brack).15 F 1.12 +(ets, and double quotes must be properly balanced and nested.)-.1 F(The)6.12 E +(re)102 618.4 Q(writing rules control remaining parsing)-.25 E F3(3)266.17 +614.4 Q F1(.)269.67 618.4 Q .32 LW 76 646 72 646 DL 80 646 76 646 DL 84 646 80 +646 DL 88 646 84 646 DL 92 646 88 646 DL 96 646 92 646 DL 100 646 96 646 DL 104 +646 100 646 DL 108 646 104 646 DL 112 646 108 646 DL 116 646 112 646 DL 120 646 +116 646 DL 124 646 120 646 DL 128 646 124 646 DL 132 646 128 646 DL 136 646 132 +646 DL 140 646 136 646 DL 144 646 140 646 DL 148 646 144 646 DL 152 646 148 646 +DL 156 646 152 646 DL 160 646 156 646 DL 164 646 160 646 DL 168 646 164 646 DL +172 646 168 646 DL 176 646 172 646 DL 180 646 176 646 DL 184 646 180 646 DL 188 +646 184 646 DL 192 646 188 646 DL 196 646 192 646 DL 200 646 196 646 DL 204 646 +200 646 DL 208 646 204 646 DL 212 646 208 646 DL 216 646 212 646 DL/F4 5 +/Times-Roman@0 SF(2)93.6 656.4 Q/F5 8/Times-Roman@0 SF(Ob)3.2 I(viously)-.12 E +2.226(,i)-.52 G 2.226(ft)135.246 659.6 S .226(he site gi)142.36 659.6 R .226(v\ +ing the error is not the originating site, the only reasonable option is to ma\ +il back to the sender)-.2 F 4.227(.A)-.44 G(lso,)492.664 659.6 Q .191 +(there are man)72 669.2 R 2.191(ym)-.12 G .19(ore error disposition options, b) +128.213 669.2 R .19(ut the)-.16 F 2.19(yo)-.12 G .19(nly ef)255.514 669.2 R .19 +(fect the error message \212 the \231return to sender\232 function is al)-.2 F +-.08(wa)-.08 G .19(ys han-).08 F(dled in one of these tw)72 678.8 Q 2(ow)-.08 G +(ays.)156.272 678.8 Q F4(3)93.6 689.2 Q F5 +(Disclaimer: Some special processing is done after re)3.2 I +(writing local names; see belo)-.2 E -.52(w.)-.2 G EP +%%Page: 6 6 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF 192.28(SMM:9-6 SENDMAIL)72 60 R 2.5<8a41>2.5 G 2.5(nI) +383.99 60 S(nter)395.94 60 Q(netw)-.15 E(ork Mail Router)-.1 E 2.5(3.2. Mail)87 +96 R(to Files and Pr)2.5 E(ograms)-.18 E/F1 10/Times-Roman@0 SF .609 +(Files and programs are le)127 112.2 R .609(gitimate message recipients.)-.15 F +.609(Files pro)5.609 F .609(vide archi)-.15 F -.25(va)-.25 G 3.109(ls).25 G .61 +(torage of mes-)445.02 112.2 R .124 +(sages, useful for project administration and history)102 124.2 R 5.124(.P)-.65 +G .124(rograms are useful as recipients in a v)318.308 124.2 R .124(ariety of) +-.25 F .69(situations, for e)102 136.2 R .691(xample, to maintain a public rep\ +ository of systems messages \(such as the Berk)-.15 F(ele)-.1 E(y)-.15 E/F2 10 +/Times-Italic@0 SF(msgs)102 148.2 Q F1(program, or the MARS system [Sattle)2.5 +E(y78]\).)-.15 E(An)127 164.4 Q 3.188(ya)-.15 G .688(ddress passing through th\ +e initial parsing algorithm as a local address \(i.e, not appear)151.698 164.4 +R(-)-.2 E .276(ing to be a v)102 176.4 R .276 +(alid address for another mailer\) is scanned for tw)-.25 F 2.776(os)-.1 G .277 +(pecial cases.)362.128 176.4 R .277(If pre\214x)5.277 F .277(ed by a v)-.15 F +(erti-)-.15 E .18(cal bar \(\231)102 188.4 R .833<7c9a>.833 G 2.68(\)t)-.833 G +.179(he rest of the address is processed as a shell command.)156.456 188.4 R +.179(If the user name be)5.179 F .179(gins with a)-.15 F(slash mark \(\231/)102 +200.4 Q(\232\) the name is used as a \214le name, instead of a login name.).833 +E .241(Files that ha)127 216.6 R .541 -.15(ve s)-.2 H .241 +(etuid or setgid bits set b).15 F .241(ut no e)-.2 F -.15(xe)-.15 G .241 +(cute bits set ha).15 F .541 -.15(ve t)-.2 H .241(hose bits honored if).15 F F2 +(send-)2.742 E(mail)102 228.6 Q F1(is running as root.)2.5 E F0 2.5 +(3.3. Aliasing,)87 252.6 R -.25(Fo)2.5 G(rwarding, Inclusion).25 E F2(Sendmail) +127 268.8 Q F1 1.075(reroutes mail three w)3.575 F 3.575(ays. Aliasing)-.1 F +1.074(applies system wide.)3.575 F -.15(Fo)6.074 G(rw).15 E 1.074(arding allo) +-.1 F 1.074(ws each)-.25 F .233 +(user to reroute incoming mail destined for that account.)102 280.8 R .233 +(Inclusion directs)5.233 F F2(sendmail)2.733 E F1 .233(to read a \214le for) +2.733 F 2.5(al)102 292.8 S +(ist of addresses, and is normally used in conjunction with aliasing.)111.72 +292.8 Q F0 2.5(3.3.1. Aliasing)102 316.8 R F1 1.554 +(Aliasing maps names to address lists using a system-wide \214le.)142 333 R +1.553(This \214le is inde)6.553 F -.15(xe)-.15 G 4.053(dt).15 G(o)499 333 Q 1.1 +(speed access.)117 345 R 1.101(Only names that parse as local are allo)6.1 F +1.101(wed as aliases; this guarantees a unique)-.25 F -.1(ke)117 357 S 2.5(y\() +-.05 G(since there are no nicknames for the local host\).)137.02 357 Q F0 2.5 +(3.3.2. F)102 381 R(orwarding)-.25 E F1 .651 +(After aliasing, recipients that are local and v)142 397.2 R .651 +(alid are check)-.25 F .65(ed for the e)-.1 F .65(xistence of a \231.for)-.15 F +(-)-.2 E -.1(wa)117 409.2 S .493(rd\232 \214le in their home directory).1 F +5.493(.I)-.65 G 2.994(fi)264.178 409.2 S 2.994(te)273.282 409.2 S .494 +(xists, the message is)283.346 409.2 R F2(not)2.994 E F1 .494 +(sent to that user)2.994 F 2.994(,b)-.4 G .494(ut rather to)459.132 409.2 R .37 +(the list of users in that \214le.)117 421.2 R .37 +(Often this list will contain only one address, and the feature will be)5.37 F +(used for netw)117 433.2 Q(ork mail forw)-.1 E(arding.)-.1 E -.15(Fo)142 449.4 +S(rw).15 E 1.151(arding also permits a user to specify a pri)-.1 F -.25(va)-.25 +G 1.152(te incoming mailer).25 F 6.152(.F)-.55 G 1.152(or e)437.346 449.4 R +1.152(xample, for)-.15 F(-)-.2 E -.1(wa)117 461.4 S(rding to:).1 E -2.5 .833 +("| /)157 477.6 T(usr/local/ne)-.833 E(wmail myname")-.25 E(will use a dif)117 +493.8 Q(ferent incoming mailer)-.25 E(.)-.55 E F0 2.5(3.3.3. Inclusion)102 +517.8 R F1(Inclusion is speci\214ed in RFC 733 [Crock)142 534 Q(er77a] syntax:) +-.1 E(:Include: pathname)157 550.2 Q .391 +(An address of this form reads the \214le speci\214ed by)117 566.4 R F2 +(pathname)2.891 E F1 .391(and sends to all users listed in that)2.891 F +(\214le.)117 578.4 Q .644(The intent is)142 594.6 R F2(not)3.144 E F1 .644 +(to support direct use of this feature, b)3.144 F .644 +(ut rather to use this as a subset of)-.2 F 2.5(aliasing. F)117 606.6 R(or e) +-.15 E(xample, an alias of the form:)-.15 E +(project: :include:/usr/project/userlist)157 622.8 Q 1.93(is a method of letti\ +ng a project maintain a mailing list without interaction with the system)117 +639 R(administration, e)117 651 Q -.15(ve)-.25 G 2.5(ni).15 G 2.5(ft)203.54 651 +S(he alias \214le is protected.)212.15 651 Q 2.024(It is not necessary to reb) +142 667.2 R 2.024(uild the inde)-.2 F 4.524(xo)-.15 G 4.524(nt)317.822 667.2 S +2.025(he alias database when a :include: list is)330.126 667.2 R(changed.)117 +679.2 Q EP +%%Page: 7 7 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF(SENDMAIL \212 An Inter)72 60 Q(netw)-.15 E +(ork Mail Router)-.1 E(SMM:9-7)462.9 60 Q 2.5(3.4. Message)87 96 R(Collection) +2.5 E/F1 10/Times-Roman@0 SF .857 +(Once all recipient addresses are parsed and v)127 112.2 R .857 +(eri\214ed, the message is collected.)-.15 F .856(The message)5.857 F +(comes in tw)102 124.2 Q 2.5(op)-.1 G +(arts: a message header and a message body)162.73 124.2 Q 2.5(,s)-.65 G +(eparated by a blank line.)343.42 124.2 Q +(The header is formatted as a series of lines of the form)127 140.4 Q +(\214eld-name: \214eld-v)178 156.6 Q(alue)-.25 E(Field-v)102 172.8 Q 1.366 +(alue can be split across lines by starting the follo)-.25 F 1.366 +(wing lines with a space or a tab)-.25 F 6.366(.S)-.4 G(ome)486.78 172.8 Q .211 +(header \214elds ha)102 184.8 R .511 -.15(ve s)-.2 H .211 +(pecial internal meaning, and ha).15 F .511 -.15(ve a)-.2 H .211 +(ppropriate special processing.).15 F .21(Other headers)5.21 F +(are simply passed through.)102 196.8 Q +(Some header \214elds may be added automatically)5 E 2.5(,s)-.65 G +(uch as time stamps.)413.53 196.8 Q .86(The body is a series of te)127 213 R +.861(xt lines.)-.15 F .861(It is completely uninterpreted and untouched, e) +5.861 F .861(xcept that)-.15 F 1.43(lines be)102 225 R 1.43 +(ginning with a dot ha)-.15 F 1.729 -.15(ve t)-.2 H 1.429 +(he dot doubled when transmitted o).15 F -.15(ve)-.15 G 3.929(ra).15 G 3.929 +(nS)407.213 225 S 1.429(MTP channel.)421.702 225 R(This)6.429 E -.15(ex)102 237 +S(tra dot is stripped by the recei).15 E -.15(ve)-.25 G -.55(r.).15 G F0 2.5 +(3.5. Message)87 261 R(Deli)2.5 E -.1(ve)-.1 G(ry).1 E F1 .028 +(The send queue is ordered by recei)127 277.2 R .029 +(ving host before transmission to implement message batch-)-.25 F 3.07 +(ing. Each)102 289.2 R .57(address is mark)3.07 F .57 +(ed as it is sent so rescanning the list is safe.)-.1 F .57(An ar)5.57 F .57 +(gument list is b)-.18 F .57(uilt as)-.2 F 1.138(the scan proceeds.)102 301.2 R +1.139(Mail to \214les is detected during the scan of the send list.)6.139 F +1.139(The interf)6.139 F 1.139(ace to the)-.1 F +(mailer is performed using one of the techniques described in section 2.2.)102 +313.2 Q .996(After a connection is established,)127 329.4 R/F2 10 +/Times-Italic@0 SF(sendmail)3.496 E F1(mak)3.495 E .995(es the per)-.1 F .995 +(-mailer changes to the header and)-.2 F .236(sends the result to the mailer) +102 341.4 R 5.236(.I)-.55 G 2.736(fa)228.406 341.4 S .537 -.15(ny m)238.912 +341.4 T .237(ail is rejected by the mailer).15 F 2.737(,a\215)-.4 G .237 +(ag is set to in)386.628 341.4 R -.2(vo)-.4 G .437 -.1(ke t).2 H .237 +(he return-).1 F(to-sender function after all deli)102 353.4 Q -.15(ve)-.25 G +(ry completes.).15 E F0 2.5(3.6. Queued)87 377.4 R(Messages)2.5 E F1 .163 +(If the mailer returns a \231temporary f)127 393.6 R .163(ailure\232 e)-.1 F +.162(xit status, the message is queued.)-.15 F 2.662(Ac)5.162 G .162 +(ontrol \214le is)455.336 393.6 R .85 +(used to describe the recipients to be sent to and v)102 405.6 R .851 +(arious other parameters.)-.25 F .851(This control \214le is for)5.851 F(-)-.2 +E 1.011(matted as a series of lines, each describing a sender)102 417.6 R 3.511 +(,ar)-.4 G 1.011(ecipient, the time of submission, or some)333.494 417.6 R .776 +(other salient parameter of the message.)102 429.6 R .776 +(The header of the message is stored in the control \214le, so)5.776 F(that th\ +e associated data \214le in the queue is just the temporary \214le that w)102 +441.6 Q(as originally collected.)-.1 E F0 2.5(3.7. Con\214guration)87 465.6 R +F1 .493(Con\214guration is controlled primarily by a con\214guration \214le re\ +ad at startup.)127 481.8 R F2(Sendmail)5.492 E F1(should)2.992 E +(not need to be recomplied e)102 493.8 Q(xcept)-.15 E 12.5(\(1\) T)107 510 R +2.5(oc)-.8 G(hange operating systems \(V6, V7/32V)150.91 510 Q 2.5(,4)-1.29 G +(BSD\).)313.21 510 Q 12.5(\(2\) T)107 526.2 R 2.5(or)-.8 G(emo)149.8 526.2 Q .3 +-.15(ve o)-.15 H 2.5(ri).15 G(nsert the DBM \(UNIX database\) library)192.27 +526.2 Q(.)-.65 E 12.5(\(3\) T)107 542.4 R 2.5(oc)-.8 G(hange ARP)150.91 542.4 Q +(ANET reply codes.)-.92 E 12.5(\(4\) T)107 558.6 R 2.5(oa)-.8 G +(dd headers \214elds requiring special processing.)150.91 558.6 Q .434 +(Adding mailers or changing parsing \(i.e., re)102 574.8 R .435 +(writing\) or routing information does not require recom-)-.25 F(pilation.)102 +586.8 Q 1.317(If the mail is being sent by a local user)127 603 R 3.817(,a)-.4 +G 1.317(nd the \214le \231.mailcf\232 e)303.914 603 R 1.317 +(xists in the sender')-.15 F 3.817(sh)-.55 G(ome)486.78 603 Q(directory)102 615 +Q 2.721(,t)-.65 G .221(hat \214le is read as a con\214guration \214le after th\ +e system con\214guration \214le.)145.451 615 R .222(The primary use)5.222 F +(of this feature is to add header lines.)102 627 Q 3.25(The con\214guration \ +\214le encodes macro de\214nitions, header de\214nitions, mailer de\214nitions\ +,)127 643.2 R(re)102 655.2 Q(writing rules, and options.)-.25 E F0 2.5 +(3.7.1. Macr)102 679.2 R(os)-.18 E F1 .332(Macros can be used in three w)142 +695.4 R 2.833(ays. Certain)-.1 F .333(macros transmit unstructured te)2.833 F +.333(xtual informa-)-.15 F .07(tion into the mail system, such as the name)117 +707.4 R F2(sendmail)2.57 E F1 .07 +(will use to identify itself in error messages.)2.57 F 1.247 +(Other macros transmit information from)117 719.4 R F2(sendmail)3.747 E F1 +1.247(to the con\214guration \214le for use in creating)3.747 F EP +%%Page: 8 8 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF 192.28(SMM:9-8 SENDMAIL)72 60 R 2.5<8a41>2.5 G 2.5(nI) +383.99 60 S(nter)395.94 60 Q(netw)-.15 E(ork Mail Router)-.1 E/F1 10 +/Times-Roman@0 SF .312(other \214elds \(such as ar)117 96 R .312(gument v)-.18 +F .312(ectors to mailers\); e.g., the name of the sender)-.15 F 2.811(,a)-.4 G +.311(nd the host and)442.237 96 R .848(user of the recipient.)117 108 R .848 +(Other macros are unused internally)5.848 F 3.348(,a)-.65 G .848 +(nd can be used as shorthand in the)361.142 108 R(con\214guration \214le.)117 +120 Q F0 2.5(3.7.2. Header)102 144 R(declarations)2.5 E F1 .355 +(Header declarations inform)142 160.2 R/F2 10/Times-Italic@0 SF(sendmail)2.854 +E F1 .354(of the format of kno)2.854 F .354(wn header lines.)-.25 F(Kno)5.354 E +.354(wledge of)-.25 F 2.5(af)117 172.2 S .5 -.25(ew h)127.27 172.2 T +(eader lines is b).25 E(uilt into)-.2 E F2(sendmail)2.5 E F1 2.5(,s)C +(uch as the \231From:\232 and \231Date:\232 lines.)284.59 172.2 Q 1.201(Most c\ +on\214gured headers will be automatically inserted in the outgoing message if \ +the)142 188.4 R(y)-.15 E(don')117 200.4 Q 2.5(te)-.18 G +(xist in the incoming message.)144.72 200.4 Q +(Certain headers are suppressed by some mailers.)5 E F0 2.5(3.7.3. Mailer)102 +224.4 R(declarations)2.5 E F1 1.756(Mailer declarations tell)142 240.6 R F2 +(sendmail)4.256 E F1 1.756(of the v)4.256 F 1.756(arious mailers a)-.25 F -.25 +(va)-.2 G 1.756(ilable to it.).25 F 1.755(The de\214nition)6.755 F .119 +(speci\214es the internal name of the mailer)117 252.6 R 2.619(,t)-.4 G .12 +(he pathname of the program to call, some \215ags associ-)285.183 252.6 R 2.036 +(ated with the mailer)117 264.6 R 4.536(,a)-.4 G 2.036(nd an ar)213.894 264.6 R +2.036(gument v)-.18 F 2.036(ector to be used on the call; this v)-.15 F 2.035 +(ector is macro-)-.15 F -.15(ex)117 276.6 S(panded before use.).15 E F0 2.5 +(3.7.4. Addr)102 300.6 R(ess r)-.18 E(ewriting rules)-.18 E F1 .458 +(The heart of address parsing in)142 316.8 R F2(sendmail)2.959 E F1 .459 +(is a set of re)2.959 F .459(writing rules.)-.25 F .459(These are an ordered) +5.459 F .561(list of pattern-replacement rules, \(some)117 328.8 R .561 +(what lik)-.25 F 3.061(eap)-.1 G .561(roduction system, e)328.867 328.8 R .56 +(xcept that order is criti-)-.15 F 1.905 +(cal\), which are applied to each address.)117 340.8 R 1.905(The address is re) +6.905 F 1.906(written te)-.25 F 1.906(xtually until it is either)-.15 F(re)117 +352.8 Q .308(written into a special canonical form \(i.e., a \(mailer)-.25 F +2.807(,h)-.4 G .307(ost, user\) 3-tuple, such as {arpanet, usc-)342.118 352.8 R +.64(isif, postel} representing the address \231postel@usc-isif\232\), or it f) +117 364.8 R .641(alls of)-.1 F 3.141(ft)-.25 G .641(he end.)406.466 364.8 R +.641(When a pattern)5.641 F(matches, the rule is reapplied until it f)117 376.8 +Q(ails.)-.1 E 1.222 +(The con\214guration \214le also supports the editing of addresses into dif)142 +393 R 1.221(ferent formats.)-.25 F -.15(Fo)6.221 G(r).15 E -.15(ex)117 405 S +(ample, an address of the form:).15 E(ucsfcgl!tef)157 421.2 Q +(might be mapped into:)117 437.4 Q(tef@ucsfcgl.UUCP)157 453.6 Q +(to conform to the domain syntax.)117 469.8 Q -.35(Tr)5 G +(anslations can also be done in the other direction.).35 E F0 2.5 +(3.7.5. Option)102 493.8 R(setting)2.5 E F1 1.168(There are se)142 510 R -.15 +(ve)-.25 G 1.169(ral options that can be set from the con\214guration \214le.) +.15 F 1.169(These include the)6.169 F(pathnames of v)117 522 Q +(arious support \214les, timeouts, def)-.25 E(ault modes, etc.)-.1 E F0 2.5 +(4. COMP)72 546 R(ARISON WITH O)-.74 E(THER MAILERS)-.4 E 2.5(4.1. Deli)87 570 +R -.1(ve)-.1 G(rmail).1 E F2(Sendmail)127 586.2 Q F1(is an outgro)2.5 E(wth of) +-.25 E F2(delivermail)2.5 E F1 5(.T)C(he primary dif)301.18 586.2 Q +(ferences are:)-.25 E 12.5(\(1\) Con\214guration)107 602.4 R .273 +(information is not compiled in.)2.773 F .272(This change simpli\214es man) +5.273 F 2.772(yo)-.15 G 2.772(ft)445.686 602.4 S .272(he problems)454.568 602.4 +R(of mo)133.66 614.4 Q(ving to other machines.)-.15 E(It also allo)5 E +(ws easy deb)-.25 E(ugging of ne)-.2 E 2.5(wm)-.25 G(ailers.)413.89 614.4 Q +12.5(\(2\) Address)107 630.6 R .681(parsing is more \215e)3.181 F 3.182 +(xible. F)-.15 F .682(or e)-.15 F(xample,)-.15 E F2(delivermail)3.182 E F1 .682 +(only supported one g)3.182 F(ate)-.05 E -.1(wa)-.25 G 3.182(yt).1 G(o)499 +630.6 Q(an)133.66 642.6 Q 2.817(yn)-.15 G(etw)155.767 642.6 Q .317 +(ork, whereas)-.1 F F2(sendmail)2.817 E F1 .317(can be sensiti)2.817 F .616 +-.15(ve t)-.25 H 2.816(oh).15 G .316(ost names and reroute to dif)345.224 642.6 +R .316(ferent g)-.25 F(ate-)-.05 E -.1(wa)133.66 654.6 S(ys.).1 E 12.5(\(3\) F) +107 670.8 R(orw)-.15 E 1.627(arding and :include: features eliminate the requi\ +rement that the system alias \214le be)-.1 F .074(writable by an)133.66 682.8 R +2.574(yu)-.15 G .073 +(ser \(or that an update program be written, or that the system administration) +203.442 682.8 R(mak)133.66 694.8 Q 2.5(ea)-.1 G(ll changes\).)162.16 694.8 Q +(\(4\))107 711 Q F2(Sendmail)133.66 711 Q F1 .4 +(supports message batching across netw)2.9 F .401 +(orks when a message is being sent to mul-)-.1 F(tiple recipients.)133.66 723 Q +EP +%%Page: 9 9 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF(SENDMAIL \212 An Inter)72 60 Q(netw)-.15 E +(ork Mail Router)-.1 E(SMM:9-9)462.9 60 Q/F1 10/Times-Roman@0 SF 12.5(\(5\) A) +107 96 R .875(mail queue is pro)3.375 F .874(vided in)-.15 F/F2 10 +/Times-Italic@0 SF(sendmail.)3.374 E F1 .874(Mail that cannot be deli)5.874 F +-.15(ve)-.25 G .874(red immediately b).15 F .874(ut can)-.2 F 1.063 +(potentially be deli)133.66 108 R -.15(ve)-.25 G 1.064 +(red later is stored in this queue for a later retry).15 F 6.064(.T)-.65 G +1.064(he queue also pro-)427.218 108 R .896(vides a b)133.66 120 R(uf)-.2 E +.896(fer ag)-.25 F .895 +(ainst system crashes; after the message has been collected it may be reli-) +-.05 F(ably redeli)133.66 132 Q -.15(ve)-.25 G(red e).15 E -.15(ve)-.25 G 2.5 +(ni).15 G 2.5(ft)224.22 132 S(he system crashes during the initial deli)232.83 +132 Q -.15(ve)-.25 G(ry).15 E(.)-.65 E(\(6\))107 148.2 Q F2(Sendmail)133.66 +148.2 Q F1 .197(uses the netw)2.696 F .197(orking support pro)-.1 F .197 +(vided by 4.2BSD to pro)-.15 F .197(vide a direct interf)-.15 F .197(ace net-) +-.1 F -.1(wo)133.66 160.2 S .07(rks such as the ARP).1 F .07 +(ANET and/or Ethernet using SMTP \(the Simple Mail T)-.92 F .07(ransfer Proto-) +-.35 F(col\) o)133.66 172.2 Q -.15(ve)-.15 G 2.5(raT).15 G(CP/IP connection.) +184.73 172.2 Q F0 2.5(4.2. MMDF)87 196.2 R F1 .957(MMDF [Crock)127 212.4 R .957 +(er79] spans a wider problem set than)-.1 F F2(sendmail)3.458 E F1 5.958(.F)C +.958(or e)395.058 212.4 R .958(xample, the domain of)-.15 F .721 +(MMDF includes a \231phone netw)102 224.4 R .721(ork\232 mailer)-.1 F 3.221(,w) +-.4 G(hereas)290.516 224.4 Q F2(sendmail)3.221 E F1 .721(calls on pree)3.221 F +.72(xisting mailers in most)-.15 F(cases.)102 236.4 Q .175(MMDF and)127 252.6 R +F2(sendmail)2.675 E F1 .175 +(both support aliasing, customized mailers, message batching, automatic)2.675 F +(forw)102 264.6 Q .792(arding to g)-.1 F(ate)-.05 E -.1(wa)-.25 G .792 +(ys, queueing, and retransmission.).1 F .792(MMDF supports tw)5.792 F .792 +(o-stage timeout, which)-.1 F F2(sendmail)102 276.6 Q F1(does not support.)2.5 +E(The con\214guration for MMDF is compiled into the code)127 294.8 Q/F3 7 +/Times-Roman@0 SF(4)348.65 290.8 Q F1(.)352.15 294.8 Q .037 +(Since MMDF does not consider backw)127 311 R .037 +(ards compatibility as a design goal, the address parsing)-.1 F(is simpler b) +102 323 Q(ut much less \215e)-.2 E(xible.)-.15 E 1.159(It is some)127 341.2 R +1.159(what harder to inte)-.25 F 1.159(grate a ne)-.15 F 3.659(wc)-.25 G +(hannel)302.802 341.2 Q F3(5)329.462 337.2 Q F1 1.159(into MMDF)336.621 341.2 R +6.16(.I)-.8 G 3.66(np)397.59 341.2 S(articular)411.25 341.2 Q 3.66(,M)-.4 G +1.16(MDF must)459.22 341.2 R(kno)102 353.2 Q 3.225(wt)-.25 G .725(he location \ +and format of host tables for all channels, and the channel must speak a speci\ +al)129.975 353.2 R 2.525(protocol. This)102 365.2 R(allo)2.525 E .025 +(ws MMDF to do additional v)-.25 F .025(eri\214cation \(such as v)-.15 F .025 +(erifying host names\) at submis-)-.15 F(sion time.)102 377.2 Q 1.761 +(MMDF strictly separates the submission and deli)127 393.4 R -.15(ve)-.25 G +1.761(ry phases.).15 F(Although)6.761 E F2(sendmail)4.261 E F1 1.76(has the) +4.261 F .784(concept of each of these stages, the)102 405.4 R 3.284(ya)-.15 G +.784(re inte)260.068 405.4 R .785(grated into one program, whereas in MMDF the) +-.15 F 3.285(ya)-.15 G(re)496.23 405.4 Q(split into tw)102 417.4 Q 2.5(op)-.1 G +(rograms.)162.19 417.4 Q F0 2.5(4.3. Message)87 441.4 R(Pr)2.5 E +(ocessing Module)-.18 E F1 .925 +(The Message Processing Module \(MPM\) discussed by Postel [Postel79b] matches) +127 457.6 R F2(sendmail)3.425 E F1 1.364 +(closely in terms of its basic architecture.)102 469.6 R(Ho)6.364 E(we)-.25 E +-.15(ve)-.25 G 2.164 -.4(r, l).15 H(ik).4 E 3.864(eM)-.1 G(MDF)347.526 469.6 Q +3.864(,t)-.8 G 1.365(he MPM includes the netw)377.54 469.6 R(ork)-.1 E(interf) +102 481.6 Q(ace softw)-.1 E(are as part of its domain.)-.1 E .408 +(MPM also postulates a duple)127 497.8 R 2.907(xc)-.15 G .407 +(hannel to the recei)256.937 497.8 R -.15(ve)-.25 G 1.207 -.4(r, a).15 H 2.907 +(sd).4 G .407(oes MMDF)365.362 497.8 R 2.907(,t)-.8 G .407(hus allo)419.546 +497.8 R .407(wing simpler)-.25 F .302 +(handling of errors by the mailer than is possible in)102 509.8 R F2(sendmail) +2.802 E F1 5.302(.W)C .302(hen a message queued by)362.24 509.8 R F2(sendmail) +2.802 E F1 .23(is sent, an)102 521.8 R 2.73(ye)-.15 G .23 +(rrors must be returned to the sender by the mailer itself.)154.2 521.8 R .229 +(Both MPM and MMDF mail-)5.229 F .883(ers can return an immediate error respon\ +se, and a single error processor can create an appropriate)102 533.8 R +(response.)102 545.8 Q 2.24 +(MPM prefers passing the message as a structured object, with type-length-v)127 +564 R 2.24(alue tuples)-.25 F F3(6)498 560 Q F1(.)501.5 564 Q .874(Such a con) +102 576 R -.15(ve)-.4 G .874(ntion requires a much higher de).15 F .875 +(gree of cooperation between mailers than is required)-.15 F(by)102 588 Q F2 +(sendmail)2.796 E F1 5.296(.M)C .296(PM also assumes a uni)167.592 588 R -.15 +(ve)-.25 G .296(rsally agreed upon internet name space \(with each address).15 +F(in the form of a net-host-user tuple\), which)102 600 Q F2(sendmail)2.5 E F1 +(does not.)2.5 E .32 LW 76 642 72 642 DL 80 642 76 642 DL 84 642 80 642 DL 88 +642 84 642 DL 92 642 88 642 DL 96 642 92 642 DL 100 642 96 642 DL 104 642 100 +642 DL 108 642 104 642 DL 112 642 108 642 DL 116 642 112 642 DL 120 642 116 642 +DL 124 642 120 642 DL 128 642 124 642 DL 132 642 128 642 DL 136 642 132 642 DL +140 642 136 642 DL 144 642 140 642 DL 148 642 144 642 DL 152 642 148 642 DL 156 +642 152 642 DL 160 642 156 642 DL 164 642 160 642 DL 168 642 164 642 DL 172 642 +168 642 DL 176 642 172 642 DL 180 642 176 642 DL 184 642 180 642 DL 188 642 184 +642 DL 192 642 188 642 DL 196 642 192 642 DL 200 642 196 642 DL 204 642 200 642 +DL 208 642 204 642 DL 212 642 208 642 DL 216 642 212 642 DL/F4 5/Times-Roman@0 +SF(4)93.6 652.4 Q/F5 8/Times-Roman@0 SF .179 +(Dynamic con\214guration tables are currently being considered for MMDF; allo) +3.2 J .18(wing the installer to select either compiled or dy-)-.2 F +(namic tables.)72 665.2 Q F4(5)93.6 675.6 Q F5(The MMDF equi)3.2 I -.2(va)-.2 G +(lent of a).2 E/F6 8/Times-Italic@0 SF(sendmail)2 E F5(\231mailer)2 E -.56 +<2e9a>-.44 G F4(6)93.6 689.2 Q F5(This is similar to the NBS standard.)3.2 I EP +%%Page: 10 10 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF 187.28(SMM:9-10 SENDMAIL)72 60 R 2.5<8a41>2.5 G 2.5(nI) +383.99 60 S(nter)395.94 60 Q(netw)-.15 E(ork Mail Router)-.1 E 2.5(5. EV)72 96 +R(ALU)-1.35 E -.95(AT)-.6 G(IONS AND FUTURE PLANS).95 E/F1 10/Times-Italic@0 SF +(Sendmail)112 112.2 Q/F2 10/Times-Roman@0 SF 1.851(is designed to w)4.351 F +1.851(ork in a nonhomogeneous en)-.1 F 4.352(vironment. Ev)-.4 F 1.852 +(ery attempt is made to)-.15 F -.2(avo)87 124.2 S 1.037 +(id imposing unnecessary constraints on the underlying mailers.).2 F 1.036 +(This goal has dri)6.036 F -.15(ve)-.25 G 3.536(nm).15 G 1.036(uch of the) +461.938 124.2 R 2.723(design. One)87 136.2 R .223(of the major problems has be\ +en the lack of a uniform address space, as postulated in [Pos-)2.723 F +(tel79a] and [Postel79b].)87 148.2 Q 2.647(An)112 164.4 S .147(onuniform addre\ +ss space implies that a path will be speci\214ed in all addresses, either e) +126.867 164.4 R(xplicitly)-.15 E .472 +(\(as part of the address\) or implicitly \(as with implied forw)87 176.4 R +.473(arding to g)-.1 F(ate)-.05 E -.1(wa)-.25 G 2.973(ys\). This).1 F .473 +(restriction has the)2.973 F .493(unpleasant ef)87 188.4 R .493 +(fect of making replying to messages e)-.25 F .493(xceedingly dif)-.15 F .493 +(\214cult, since there is no one \231address\232)-.25 F(for an)87 200.4 Q 2.5 +(yp)-.15 G(erson, b)122.95 200.4 Q(ut only a w)-.2 E +(ay to get there from where)-.1 E -.15(ve)-.25 G 2.5(ry).15 G(ou are.)324.7 +200.4 Q(Interf)112 216.6 Q .448(acing to mail programs that were not initially\ + intended to be applied in an internet en)-.1 F(viron-)-.4 E(ment has been ama\ +zingly successful, and has reduced the job to a manageable task.)87 228.6 Q F1 +(Sendmail)112 244.8 Q F2 2.906(has kno)5.406 F 2.906(wledge of a fe)-.25 F +5.406(wd)-.25 G(if)271.126 244.8 Q 2.906(\214cult en)-.25 F 2.906(vironments b) +-.4 F 2.906(uilt in.)-.2 F 2.905(It generates ARP)7.906 F(ANET)-.92 E .648(FTP\ +/SMTP compatible error messages \(prepended with three-digit numbers [Neigus73\ +, Postel74, Pos-)87 256.8 R .771(tel82]\) as necessary)87 268.8 R 3.271(,o)-.65 +G .771(ptionally generates UNIX-style \231From\232 lines on the front of messa\ +ges for some)177.523 268.8 R 1.669(mailers, and kno)87 280.8 R 1.669(ws ho)-.25 +F 4.169(wt)-.25 G 4.169(op)195.666 280.8 S 1.669(arse the same lines on input.) +209.835 280.8 R 1.67(Also, error handling has an option cus-)6.67 F +(tomized for BerkNet.)87 292.8 Q 1.482(The decision to a)112 309 R -.2(vo)-.2 G +1.482(id doing an).2 F 3.982(yt)-.15 G 1.481(ype of deli)254.222 309 R -.15(ve) +-.25 G 1.481(ry where possible \(e).15 F -.15(ve)-.25 G 1.481 +(n, or perhaps especially).15 F(,)-.65 E .574(local deli)87 321 R -.15(ve)-.25 +G .574(ry\) has turned out to be a good idea.).15 F(Ev)5.574 E .574 +(en with local deli)-.15 F -.15(ve)-.25 G(ry).15 E 3.074(,t)-.65 G .575 +(here are issues of the loca-)394.776 321 R .469(tion of the mailbox, the form\ +at of the mailbox, the locking protocol used, etc., that are best decided by)87 +333 R .038(other programs.)87 345 R .038(One surprisingly major anno)5.038 F +.038(yance in man)-.1 F 2.538(yi)-.15 G .038 +(nternet mailers is that the location and for)333.684 345 R(-)-.2 E .138 +(mat of local mail is b)87 357 R .138(uilt in.)-.2 F .137 +(The feeling seems to be that local mail is so common that it should be ef) +5.137 F<8c2d>-.25 E 3.045(cient. This)87 369 R .545 +(feeling is not born out by our e)3.045 F .545(xperience; on the contrary)-.15 +F 3.045(,t)-.65 G .545(he location and format of mail-)376.575 369 R(box)87 381 +Q(es seems to v)-.15 E(ary widely from system to system.)-.25 E .681 +(The ability to automatically generate a response to incoming mail \(by forw) +112 397.2 R .68(arding mail to a pro-)-.1 F .435 +(gram\) seems useful \(\231I am on v)87 409.2 R .435 +(acation until late August....)-.25 F 2.935(\232\) b)-.7 F .435 +(ut can create problems such as forw)-.2 F(ard-)-.1 E .143(ing loops \(tw)87 +421.2 R 2.643(op)-.1 G .143(eople on v)152.609 421.2 R .143(acation whose prog\ +rams send notes back and forth, for instance\) if these pro-)-.25 F .732 +(grams are not well written.)87 433.2 R 3.232(Ap)5.732 G .732 +(rogram could be written to do standard tasks correctly)218.592 433.2 R 3.233 +(,b)-.65 G .733(ut this w)450.404 433.2 R(ould)-.1 E(solv)87 445.2 Q 2.5(et) +-.15 G(he general case.)113.24 445.2 Q .225 +(It might be desirable to implement some form of load limiting.)112 461.4 R +2.725(Ia)5.225 G 2.724(mu)380.8 461.4 S(na)396.304 461.4 Q -.1(wa)-.15 G .224 +(re of an).1 F 2.724(ym)-.15 G .224(ail system)463.496 461.4 R +(that addresses this problem, nor am I a)87 473.4 Q -.1(wa)-.15 G(re of an).1 E +2.5(yr)-.15 G(easonable solution at this time.)294.05 473.4 Q .113(The con\214\ +guration \214le is currently practically inscrutable; considerable con)112 +489.6 R -.15(ve)-.4 G .114(nience could be real-).15 F(ized with a higher)87 +501.6 Q(-le)-.2 E -.15(ve)-.25 G 2.5(lf).15 G(ormat.)186.93 501.6 Q .778(It se\ +ems clear that common protocols will be changing soon to accommodate changing \ +require-)112 517.8 R 2.774(ments and en)87 529.8 R 5.274(vironments. These)-.4 +F 2.774(changes will include modi\214cations to the message header \(e.g.,) +5.274 F .859([NBS80]\) or to the body of the message itself \(such as for mult\ +imedia messages [Postel80]\).)87 541.8 R(Experi-)5.859 E +(ence indicates that these changes should be relati)87 553.8 Q -.15(ve)-.25 G +(ly tri).15 E(vial to inte)-.25 E(grate into the e)-.15 E(xisting system.)-.15 +E .811(In tightly coupled en)112 570 R .812(vironments, it w)-.4 F .812 +(ould be nice to ha)-.1 F 1.112 -.15(ve a n)-.2 H .812(ame serv).15 F .812 +(er such as Grapvine [Bir)-.15 F(-)-.2 E .095(rell82] inte)87 582 R .095 +(grated into the mail system.)-.15 F .095(This w)5.095 F .095(ould allo)-.1 F +2.594(was)-.25 G .094(ite such as \231Berk)330.768 582 R(ele)-.1 E .094 +(y\232 to appear as a single)-.15 F 2.606 +(host, rather than as a collection of hosts, and w)87 594 R 2.606(ould allo)-.1 +F 5.106(wp)-.25 G 2.606(eople to mo)352.786 594 R 2.906 -.15(ve t)-.15 H 2.606 +(ransparently among).15 F 1.664(machines without ha)87 606 R 1.664 +(ving to change their addresses.)-.2 F 1.664(Such a f)6.664 F 1.664(acility w) +-.1 F 1.663(ould require an automatically)-.1 F .428 +(updated database and some method of resolving con\215icts.)87 618 R .428 +(Ideally this w)5.428 F .428(ould be ef)-.1 F(fecti)-.25 E .728 -.15(ve e)-.25 +H -.15(ve)-.1 G 2.928(nw).15 G(ithout)480.66 618 Q .184 +(all hosts being under a single management.)87 630 R(Ho)5.184 E(we)-.25 E -.15 +(ve)-.25 G .984 -.4(r, i).15 H 2.684(ti).4 G 2.683(sn)317.576 630 S .183 +(ot clear whether this feature should be inte-)329.149 630 R +(grated into the aliasing f)87 642 Q(acility or should be considered a \231v) +-.1 E(alue added\232 feature outside)-.25 E F1(sendmail)2.5 E F2(itself.)2.5 E +.79(As a more interesting case, the CSNET name serv)112 658.2 R .791 +(er [Solomon81] pro)-.15 F .791(vides an f)-.15 F .791(acility that goes)-.1 F +(be)87 670.2 Q .375(yond a single tightly-coupled en)-.15 F 2.875 +(vironment. Such)-.4 F 2.875(af)2.875 G .375(acility w)308.675 670.2 R .374 +(ould normally e)-.1 F .374(xist outside of)-.15 F F1(sendmail)2.874 E F2(ho)87 +682.2 Q(we)-.25 E -.15(ve)-.25 G -.55(r.).15 G EP +%%Page: 11 11 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Bold@0 SF(SENDMAIL \212 An Inter)72 60 Q(netw)-.15 E +(ork Mail Router)-.1 E(SMM:9-11)457.9 60 Q -.55(AC)72 96 S(KNO).55 E +(WLEDGEMENTS)-.5 E/F1 10/Times-Roman@0 SF 1.203(Thanks are due to K)97 112.2 R +1.204 +(urt Shoens for his continual cheerful assistance and good advice, Bill Jo)-.15 +F 3.704(yf)-.1 G(or)495.67 112.2 Q .102 +(pointing me in the correct direction \(o)72 124.2 R -.15(ve)-.15 G 2.602(ra) +.15 G .102(nd o)244.324 124.2 R -.15(ve)-.15 G .102 +(r\), and Mark Horton for more advice, prodding, and man).15 F(y)-.15 E .453 +(of the good ideas.)72 136.2 R -.15(Ku)5.453 G .453 +(rt and Eric Schmidt are to be credited for using).15 F/F2 10/Times-Italic@0 SF +(delivermail)2.953 E F1 .453(as a serv)2.953 F .453(er for their pro-)-.15 F +1.663(grams \()72 148.2 R F2(Mail)A F1 1.663(and BerkNet respecti)4.163 F -.15 +(ve)-.25 G 1.663(ly\) before an).15 F 4.163(ys)-.15 G 1.663 +(ane person should ha)291.091 148.2 R -.15(ve)-.2 G 4.163(,a).15 G 1.662 +(nd making the necessary)400.423 148.2 R .078 +(modi\214cations promptly and happily)72 160.2 R 5.078(.E)-.65 G .078(ric g) +228.332 160.2 R -2.25 -.2(av e)-.05 H .079 +(me considerable advice about the perils of netw)2.778 F .079(ork softw)-.1 F +(are)-.1 E .179(which sa)72 172.2 R -.15(ve)-.2 G 2.679(dm).15 G 2.679(ea) +131.998 172.2 S 2.679(nu)143.557 172.2 S(nkno)156.236 172.2 Q .178 +(wn amount of w)-.25 F .178(ork and grief.)-.1 F .178 +(Mark did the original implementation of the DBM)5.178 F -.15(ve)72 184.2 S +.341(rsion of aliasing, installed the VFORK code, wrote the current v).15 F +.341(ersion of)-.15 F F2(rmail)2.841 E F1 2.841(,a)C .341(nd w)411.083 184.2 R +.342(as the person who)-.1 F .61(really con)72 196.2 R .61 +(vinced me to put the w)-.4 F .61(ork into)-.1 F F2(delivermail)3.109 E F1 .609 +(to turn it into)3.109 F F2(sendmail)3.109 E F1 5.609(.K)C .609(urt deserv) +398.753 196.2 R .609(es accolades for)-.15 F(using)72 208.2 Q F2(sendmail)2.57 +E F1 .07(when I w)2.57 F .07(as myself afraid to tak)-.1 F 2.57(et)-.1 G .07 +(he risk; ho)271.01 208.2 R 2.57(wap)-.25 G .07 +(erson can continue to be so enthusiastic in)334.92 208.2 R(the f)72 220.2 Q +(ace of so much bitter reality is be)-.1 E(yond me.)-.15 E -.15(Ku)97 236.4 S +1.505(rt, Mark, Kirk McK).15 F 1.505(usick, Marvin Solomon, and man)-.15 F +4.005(yo)-.15 G 1.504(thers ha)345.79 236.4 R 1.804 -.15(ve r)-.2 H -.25(ev).15 +G(ie).25 E 1.504(wed this paper)-.25 F 4.004(,g)-.4 G -.25(iv)483.69 236.4 S +(ing).25 E(considerable useful advice.)72 248.4 Q .846 +(Special thanks are reserv)97 264.6 R .846(ed for Mik)-.15 F 3.346(eS)-.1 G +(tonebrak)256.786 264.6 Q .846(er at Berk)-.1 F(ele)-.1 E 3.347(ya)-.15 G .847 +(nd Bob Epstein at Britton-Lee, who)356.995 264.6 R .542(both kno)72 276.6 R +.542(wingly allo)-.25 F .542(wed me to put so much w)-.25 F .541 +(ork into this project when there were so man)-.1 F 3.041(yo)-.15 G .541 +(ther things I)454.588 276.6 R(really should ha)72 288.6 Q .3 -.15(ve b)-.2 H +(een w).15 E(orking on.)-.1 E EP +%%Page: 12 12 +%%BeginPageSetup +BP +%%EndPageSetup +/F0 10/Times-Roman@0 SF(REFERENCES)256.605 132 Q 62.73([Birrell82] Birrell,)72 +148.2 R 1.084(A. D., Le)3.584 F 1.084(vin, R., Needham, R. M., and Schroeder) +-.25 F 3.584(,M)-.4 G 3.585(.D)433.49 148.2 S 1.085(., \231Grape)446.795 148.2 +R(vine:)-.25 E(An Ex)180 160.2 Q(ercise in Distrib)-.15 E(uted Computing.)-.2 E +5<9a49>-.7 G(n)348.66 160.2 Q/F1 10/Times-Italic@0 SF(Comm. A.C.M. 25,)2.5 E F0 +(4, April 82.)2.5 E 59.4([Borden79] Borden,)72 176.4 R .796 +(S., Gaines, R. S., and Shapiro, N. Z.,)3.296 F F1 .795(The MH Messa)3.295 F +.995 -.1(ge H)-.1 H .795(andling Sys-).1 F(tem: User)180 188.4 Q(s' Manual.)-.1 +E F0(R-2367-P)5 E(AF)-.92 E 5(.R)-.8 G(and Corporation.)332.06 188.4 Q +(October 1979.)5 E([Crock)72 204.6 Q 52.29(er77a] Crock)-.1 F(er)-.1 E 2.508 +(,D)-.4 G 2.508(.H)223.938 204.6 S .008(., V)236.166 204.6 R .009 +(ittal, J. J., Pogran, K. T)-.6 F .009(., and Henderson, D. A. Jr)-.74 F(.,) +-.55 E F1(Standar)2.509 E 2.509(df)-.37 G(or)495.11 204.6 Q .955(the F)180 +216.6 R .955(ormat of ARP)-1.05 F 3.454(AN)-.9 G .954(etwork T)272.978 216.6 R +-.2(ex)-.92 G 3.454(tM).2 G(essa)331.536 216.6 Q -.1(ge)-.1 G(s.).1 E F0 .954 +(RFC 733, NIC 41952.)5.954 F .954(In [Fein-)5.954 F 2.5(ler78]. No)180 228.6 R +-.15(ve)-.15 G(mber 1977.).15 E([Crock)72 244.8 Q 51.73(er77b] Crock)-.1 F(er) +-.1 E 3.04(,D)-.4 G 3.04(.H)224.47 244.8 S(.,)237.23 244.8 Q F1 -1.55 -.55 +(Fr a)3.04 H(me).55 E .54(work and Functions of the MS P)-.15 F(er)-.8 E .54 +(sonal Messa)-.1 F .74 -.1(ge S)-.1 H(ystem.).1 E F0(R-2134-ARP)180 256.8 Q +(A, Rand Corporation, Santa Monica, California.)-.92 E(1977.)5 E([Crock)72 273 +Q 56.73(er79] Crock)-.1 F(er)-.1 E 2.557(,D)-.4 G 2.557(.H)223.987 273 S .056 +(., Szurk)236.264 273 R -.25(ow)-.1 G .056(ski, E. S., and F).25 F(arber)-.15 E +2.556(,D)-.4 G 2.556(.J)374.85 273 S(.,)383.796 273 Q F1 .056 +(An Internetwork Memo Dis-)2.556 F(trib)180 285 Q 1.341(ution F)-.2 F 1.341 +(acility \212 MMDF)-.75 F(.)-1.35 E F0 1.341 +(6th Data Communication Symposium, Asilomar)6.341 F(.)-.55 E(No)180 297 Q -.15 +(ve)-.15 G(mber 1979.).15 E([Crock)72 313.2 Q 56.73(er82] Crock)-.1 F(er)-.1 E +3.383(,D)-.4 G 3.383(.H)224.813 313.2 S(.,)237.916 313.2 Q F1(Standar)3.383 E +3.383(df)-.37 G .883(or the F)288.762 313.2 R .882(ormat of Arpa Internet T) +-1.05 F -.2(ex)-.92 G 3.382(tM).2 G(essa)446.368 313.2 Q -.1(ge)-.1 G(s.).1 E +F0(RFC)5.882 E 4.197(822. Netw)180 325.2 R 1.697(ork Information Center)-.1 F +4.197(,S)-.4 G 1.698(RI International, Menlo P)333.768 325.2 R 1.698 +(ark, California.)-.15 F(August 1982.)180 337.2 Q 53.3([Metcalfe76] Metcalfe,) +72 353.4 R .727(R., and Boggs, D., \231Ethernet: Distrib)3.227 F .727(uted P) +-.2 F(ack)-.15 E .727(et Switching for Local)-.1 F(Computer Netw)180 365.4 Q +(orks\232,)-.1 E F1(Communications of the A)2.5 E(CM 19,)-.3 E F0 2.5(7. July) +2.5 F(1976.)2.5 E 60.51([Feinler78] Feinler)72 381.6 R 4.438(,E)-.4 G 1.938 +(., and Postel, J.)220.978 381.6 R(\(eds.\),)6.938 E F1(ARP)4.438 E 1.938 +(ANET Pr)-.9 F 1.938(otocol Handbook.)-.45 F F0 1.938(NIC 7104,)6.938 F(Netw) +180 393.6 Q(ork Information Center)-.1 E 2.5(,S)-.4 G +(RI International, Menlo P)304.48 393.6 Q(ark, California.)-.15 E(1978.)5 E +69.39([NBS80] National)72 409.8 R 1.46(Bureau of Standards,)3.96 F F1 1.46 +(Speci\214cation of a Dr)3.96 F 1.46(aft Messa)-.15 F 1.66 -.1(ge F)-.1 H 1.46 +(ormat Stan-)-.95 F(dar)180 421.8 Q(d.)-.37 E F0(Report No. ICST/CBOS 80-2.)5 E +(October 1980.)5 E 60.51([Neigus73] Neigus,)72 438 R(N.,)5.186 E F1 -.45(Fi) +5.186 G 2.686(le T).45 F -.15(ra)-.55 G 2.686(nsfer Pr).15 F 2.686 +(otocol for the ARP)-.45 F 5.187(AN)-.9 G(etwork.)402.599 438 Q F0 2.687 +(RFC 542, NIC)7.687 F 2.5(17759. In)180 450 R 2.5([Feinler78]. August,)2.5 F +(1973.)2.5 E([No)72 466.2 Q 55.21(witz78a] No)-.25 F 1.633 +(witz, D. A., and Lesk, M. E.,)-.25 F F1 4.132(AD)4.132 G 1.632 +(ial-Up Network of UNIX Systems.)338.9 466.2 R F0(Bell)6.632 E 5.403 +(Laboratories. In)180 478.2 R 2.904(UNIX Programmer')5.403 F 5.404(sM)-.55 G +2.904(anual, Se)356.024 478.2 R -.15(ve)-.25 G 2.904(nth Edition, V).15 F 2.904 +(olume 2.)-1.29 F(August, 1978.)180 490.2 Q([No)72 506.4 Q 54.65(witz78b] No) +-.25 F .633(witz, D. A.,)-.25 F F1 .632(Uucp Implementation Description.)3.132 +F F0 .632(Bell Laboratories.)5.632 F .632(In UNIX)5.632 F(Programmer')180 518.4 +Q 2.5(sM)-.55 G(anual, Se)248.05 518.4 Q -.15(ve)-.25 G(nth Edition, V).15 E +(olume 2.)-1.29 E(October)5 E 2.5(,1)-.4 G(978.)431.22 518.4 Q 64.39 +([Postel74] Postel,)72 534.6 R .24(J., and Neigus, N., Re)2.74 F .241 +(vised FTP Reply Codes.)-.25 F .241(RFC 640, NIC 30843.)5.241 F(In)5.241 E 2.5 +([Feinler78]. 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