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    1: **Contents**
    2: 
    3: [[!toc levels=3]]
    4: 
    5: # Mail and news
    6: 
    7: This chapter explains how to set up NetBSD to use mail and news. Only a simple
    8: but very common setup is described: the configuration of a host connected to the
    9: Internet with a modem through a provider. You can think of this chapter as the
   10: continuation of
   11: [[Setting up TCP/IP on NetBSD in practice|guide/net-practice]], assuming a
   12: similar network configuration. Even this *simple* setup proves to be difficult
   13: if you don't know where to start or if you've only read introductory or
   14: technical documentation. A general description of mail and news
   15: configuration is beyond the scope of this guide; please read a good Unix
   16: Administration book (some very good ones are listed on the NetBSD site).
   17: 
   18: This chapter also briefly describes the configuration (but not the usage) of two
   19: popular applications, mutt for mail and tin for news. The usage is not described
   20: because they are easy to use and well documented. Obviously, both mutt and tin
   21: are not mandatory choices: many other similar applications exist but I think
   22: that they are a good starting point because they are widely used, simple, work
   23: well and don't use too much disk space and memory. Both are console mode
   24: programs; if you prefer graphics applications there are also many choices for X.
   25: 
   26: In short, the programs required for the configuration described in this chapter
   27: are:
   28: 
   29:  * postfix
   30:  * fetchmail
   31:  * mutt
   32:  * tin
   33: 
   34: Of these, only postfix is installed with the base system; you can install the
   35: other programs from the NetBSD package collection, pkgsrc.
   36: 
   37: *Note*: Since NetBSD 4.0, postfix is the default MTA (Mail Transport Agent) and
   38: sendmail was removed. Also, because sendmail is widely popular and several
   39: programs like fetchmail are designed to be used with it, postfix includes a
   40: command line wrapper that accepts sendmail's commands line syntax but works with
   41: postfix. See
   42: [[!template id=man name="sendmail" section="1"]]
   43: for more details.
   44: 
   45: Before continuing, remember that none of the programs presented in this chapter
   46: is mandatory: there are other applications performing similar tasks and many
   47: users prefer them. You'll find different opinions reading the mailing lists. You
   48: can also use different strategies for sending and receiving mail: the one
   49: explained here is only a starting point; once you understand how it works you'll
   50: probably want to modify it to suit your needs or to adopt a different method
   51: altogether.
   52: 
   53: At the opposite extreme of the example presented here, there is the usage of an
   54: application like Mozilla, which does everything and frees you from the need of
   55: configuring many components: with Mozilla you can browse the Internet, send and
   56: receive mail and read news. Besides, the setup is very simple. There is a price
   57: to pay, though: Mozilla is a "closed" program that will not cooperate easily
   58: with other standard Unix utilities.
   59: 
   60: Another possibility is to use emacs to read mail and news. Emacs needs no
   61: introduction to Unix users but, in case you don't know, it is an extensible
   62: editor (although calling emacs an editor is somewhat reductive) which becomes a
   63: complete work environment, and can be used to read mail, news and to perform
   64: many operations. For many people emacs is the only environment that they need
   65: and they use it for all their work. The configuration of emacs for mail and news
   66: is described in the emacs manual.
   67: 
   68: In the rest of this chapter we will deal with a host connected to the Internet
   69: through a PPP connection via serial modem to a provider.
   70: 
   71:  * the local host's name is `ape` and the internal network is `insetti.net`,
   72:    which means that the FQDN (Fully Qualified Domain Name) is `ape.insetti.net`.
   73:  * the user's login name on ape is `carlo`.
   74:  * the provider's name is BigNet.
   75:  * the provider's mail server is `mail.bignet.it`.
   76:  * the provider's news server is `news.bignet.it`.
   77:  * the user's (`carlo`) account at the provider is `alan` with the password
   78:    `pZY9o`.
   79: 
   80: First some basic terminology:
   81: 
   82:  * *MUA (mail user agent)* -- a program to read and write mail. For example:
   83:    mutt, elm and pine but also the simple mail application installed with the
   84:    base system.
   85: 
   86:  * *MTA (mail transfer agent)* -- a program that transfers mail between two host
   87:    but also locally (on the same host). The MTA decides the path that the mail
   88:    will follow to get to the destination. On other BSD systems (but not only)
   89:    the standard MTA is sendmail, other examples are qmail, exim and Microsoft
   90:    Exchange.
   91: 
   92:  * *MDA (mail delivery agent)* -- a program, usually used by the MTA, that
   93:    delivers the mail; for example, it physically puts the messages in the
   94:    recipient's mailbox. For example, postfix uses one or more MDAs to deliver
   95:    mail, and procmail is another well-known MDA.
   96: 
   97: The following figure depicts the mail system that we want to set up. Between the
   98: local network (or the single host) and the provider there is a modem PPP
   99: connection. The *bubbles* with the thick border (postfix, fetchmail, mutt) are
  100: the programs launched manually by the user; the remaining bubbles are the
  101: programs that are launched automatically. The circled numbers refer to the
  102: logical steps of the mail cycle:
  103: 
  104: ![Structure of the mail system](/guide/images/mail1.gif)
  105: 
  106:  1. In step (1) mail is downloaded from the provider's POP server using
  107:     fetchmail, which hands messages off to postfix's sendmail wrapper to put the
  108:     messages in the user's mailbox.
  109: 
  110:  2. In step (2) the user launches mutt (or another MUA) to read mail, reply and
  111:     write new messages.
  112: 
  113:  3. In step (3) the user *sends* the mail from within mutt. Messages are
  114:     accumulated in the spool area.
  115: 
  116:  4. In step (4) the user calls postfix's sendmail wrapper to transfer the
  117:     messages to the provider's SMTP server, that will deliver them to the final
  118:     destination (possibly through other mail servers). The provider's SMTP server
  119:     acts as a *relay* for our mail.
  120: 
  121: The connection with the provider must be up only during steps (1) and (4); for
  122: the remaining steps it is not needed.
  123: 
  124: ## postfix
  125: 
  126: When an MTA must deliver a local message, it is delivered directly. If the
  127: message is intended for a different domain, the MTA must find out the address of
  128: the mail server for that domain. Postfix uses the DNS service (described in
  129: [[The Domain Name System|guide/dns]]) to find a mail exchanger handling mail for
  130: the given domain, and delivers the message to that mail server then.
  131: 
  132: Postfix is controlled by a set of configuration files and databases, of which
  133: `/etc/postfix/main.cf` and `/etc/postfix/master.cf` are the most important.
  134: 
  135: *Note*: Prior to version 1.5 of NetBSD, the mail configuration files were in
  136: `/etc` instead of `/etc/mail`. Since NetBSD 4.0, the `/etc/mail` directory is
  137: only used to store the local aliases and the corresponding
  138: [[!template id=man name="postmap" section="1"]]
  139: database.
  140: 
  141: The first problem to be solved is that the local network we are dealing with is
  142: an internal network, i.e. not directly accessible from the Internet. This means
  143: that the names used internally have no meaning on the Internet; in short,
  144: `ape.insetti.net` cannot be reached by an external host: no one will be able to
  145: reply to a mail sent with this return address (many mail systems will even
  146: reject the message as spam prevention as it comes from an unknown host). The
  147: true address, the one visible from everybody, is assigned by the provider and,
  148: therefore, it is necessary to convert the local address `carlo@ape.insetti.net`
  149: to the real address `alan@bignet.it`. Postfix, if correctly configured, will
  150: take care of this when it transfers the messages.
  151: 
  152: You'll probably also want to configure postfix in order to send the e-mails to
  153: the provider's mail server, using it as a *relay*. In the configuration
  154: described in this chapter, postfix does not directly contact the recipient's
  155: mail server (as previously described) but relays all its mail to the provider's
  156: mail server.
  157: 
  158: *Note*: The provider's mail server acts as a *relay*, which means that it
  159: delivers mail which is not destined to its own domain, to another mail server.
  160: It acts as an intermediary between two servers.
  161: 
  162: Since the connection with the provider is not always active, it is not necessary
  163: to start postfix as a daemon in `/etc/rc.conf`: you can disable it with the line
  164: `postfix=NO`. As a consequence it will be necessary to launch postfix manually
  165: when you want to transfer mail to the provider. Local mail is delivered
  166: correctly even if postfix is not active as a daemon.
  167: 
  168: Let's start configuring postfix.
  169: 
  170: ### Configuration of generic mapping
  171: 
  172: This type of configuration uses a new file `/etc/postfix/generic` which contains
  173: the hostname mapping used by postfix to rewrite the internal hostnames.
  174: 
  175: The first step is therefore to write the mapping file:
  176: 
  177:     carlo@ape.insetti.net           alan@bignet.it
  178:     root@ape.insetti.net            alan@bignet.it
  179:     news@ape.insetti.net            alan@bignet.it
  180: 
  181: These entries will map the mail sent from the users given on the left side into
  182: the globally valid email addresses given on the right, making it appear as if
  183: the mail was really sent from that address.
  184: 
  185: For the sake of efficiency, `generic` must be transformed into a binary file
  186: with the following command:
  187: 
  188:     # postmap /etc/postfix/generic
  189: 
  190: Now it's time to create the prototype configuration file which we'll use to
  191: create the postfix configuration file.
  192: 
  193:     # vi /etc/postfix/main.cf
  194: 
  195: For the sake of simplicity, we'll only show the variables you need to change:
  196: 
  197:     relayhost = mail.bignet.it
  198:     smtp_generic_maps = hash:/etc/postfix/generic
  199: 
  200: This configuration tells postfix to rewrite the addresses of type
  201: `ape.insetti.net` using the real names found in the `/etc/postfix/generic` file.
  202: It also says that mail should be sent to the `mail.bignet.it` server. The
  203: meaning of the options is described in detail in
  204: [[!template id=man name="postconf" section="5"]].
  205: 
  206: The last step is to reload the configuration. You can do that easily with:
  207: 
  208:     # /etc/rc.d/postfix reload
  209:     postfix/postfix-script: refreshing the Postfix mail system
  210: 
  211: Now everything is ready to start sending mail.
  212: 
  213: ### Testing the configuration
  214: 
  215: Postfix is finally configured and ready to work, but before sending real mail it
  216: is better to do some simple tests. First let's try sending a local e-mail with
  217: the following command (postfix's sendmail wrapper):
  218: 
  219:     $ sendmail carlo
  220:     Subject: test
  221:     
  222:     Hello world
  223:     .
  224: 
  225: Please follow exactly the example above: leave a blank line after Subject: and
  226: end the message with a line containing only one dot. Now you should be able to
  227: read the message with your mail client and verify that the From: field has been
  228: correctly rewritten.
  229: 
  230:     From: alan@bignet.it
  231: 
  232: ### Using an alternative MTA
  233: 
  234: Starting from version 1.4 of NetBSD sendmail is not called directly:
  235: 
  236:     $ ls -l /usr/sbin/sendmail
  237:     lrwxr-xr-x  1 root  wheel  21 Nov  1 01:14 /usr/sbin/sendmail@ -> /usr/sbin/mailwrapper
  238: 
  239: The purpose of mailwrapper is to allow the usage of an alternative MTA instead
  240: of postfix (for example, sendmail). If you plan to use a different mailer I
  241: suggest that you read the
  242: [[!template id=man name="mailwrapper" section="8"]]
  243: and the
  244: [[!template id=man name="mailer.conf" section="5"]]
  245: manpages, which are very clear.
  246: 
  247: ## fetchmail
  248: 
  249: If someone sends me mail, it is received and stored by the provider, and not
  250: automatically transferred to the local hosts; therefore it is necessary to
  251: download it. Fetchmail is a very popular program that downloads mail from a
  252: remote mail server (using e.g. the Post Office Protocol, POP) and forwards it to
  253: the local system for delivery (usually using postfix's sendmail wrapper). It is
  254: powerful yet easy to use and configure: after installation, the file
  255: `~/.fetchmailrc` must be created and the program is ready to run
  256: (`~/.fetchmailrc` contains a password so appropriate permissions on the file are
  257: required).
  258: 
  259: This is an example `.fetchmailrc`:
  260: 
  261:     poll mail.bignet.it
  262:     protocol POP3
  263:     username alan there with password pZY9o is carlo here
  264:     flush
  265:     mda "/usr/sbin/sendmail -oem %T"
  266: 
  267: The last line (`mda ...`) is used only if postfix is not active as daemon on the
  268: system. Please note that the POP-mail server indicated in this file
  269: (mail.bignet.it) is only used to retrieve mails, and that it is not necessary
  270: the same as the mail relay used by postfix to send out mails.
  271: 
  272: After setting up the `.fetchmailrc` file, the following command can be used to
  273: download and deliver mail to the local system:
  274: 
  275:     $ fetchmail
  276: 
  277: The messages can now be read with mutt.
  278: 
  279: ## Reading and writing mail with mutt
  280: 
  281: Mutt is one of the most popular mail programs: it is *lightweight*, easy to use
  282: and has lots of features. The man page mutt is very bare bones; the real
  283: documentation is in `/usr/pkg/share/doc/mutt/`, in particular `manual.txt`.
  284: 
  285: Mutt's configuration is defined by the `~/.muttrc` file. The easiest way to
  286: create it is to copy mutt's example muttrc file (usually
  287: `/usr/pkg/share/examples/mutt/sample.muttrc`) to the home directory and modify
  288: it. The following example shows how to achieve some results:
  289: 
  290:  * Save a copy of sent mail.
  291:  * Define a directory and two files for incoming and outgoing mail saved by mutt
  292:    (in this example the directory is `~/Mail` and the files are `incoming` and
  293:    `outgoing`).
  294:  * Define some colors.
  295:  * Define an alias.
  296: 
  297:     set copy=yes
  298:     set edit_headers
  299:     set folder="~/Mail"
  300:     unset force_name
  301:     set mbox="~/Mail/incoming"
  302:     set record="~/Mail/outgoing"
  303:     unset save_name
  304:     
  305:     bind pager <up> previous-page
  306:     bind pager <down> next-page
  307:     
  308:     color normal white black
  309:     color hdrdefault blue black
  310:     color indicator white blue
  311:     color markers red black
  312:     color quoted cyan black
  313:     color status white blue
  314:     color error red white
  315:     color underline yellow black
  316:     
  317:     mono quoted standout
  318:     mono hdrdefault underline
  319:     mono indicator underline
  320:     mono status bold
  321:     
  322:     alias pippo Pippo Verdi <pippo.verdi@pluto.net>
  323: 
  324: To start mutt:
  325: 
  326:     $ mutt
  327: 
  328: Please note that mutt supports color, but this depends on the terminal settings.
  329: Under X you can use "xterm-color", for example:
  330: 
  331:     $ env TERM=xterm-color mutt
  332: 
  333: ## Strategy for receiving mail
  334: 
  335: This section describes a simple method for receiving and reading mail. The
  336: connection to the provider is activated only for the time required to download
  337: the messages; mail is then read offline.
  338: 
  339:  1. Activate the connection to the provider.
  340:  2. Run `fetchmail`.
  341:  3. Deactivate the connection.
  342:  4. Read mail with mutt.
  343: 
  344: ## Strategy for sending mail
  345: 
  346: When mail has been written and *sent* with mutt, the messages must be
  347: transferred to the provider with postfix. Mail is sent from mutt with the `y`
  348: command, but this does not really send it; the messages are enqueued in the
  349: spool area; if postfix is not active as a daemon it is necessary to start it
  350: manually or the messages will remain on the hard disk. The necessary steps are:
  351: 
  352:  1. Write mail with mutt, send it and exit mutt. You can check if and what
  353:     messages are in the postfix mail queue using the
  354:     [[!template id=man name="mailq" section="1"]]
  355:     program.
  356:  2. Activate the connection with the provider.
  357:  3. If your provider requires you to do "SMTP-after-POP", i.e. it first wants to
  358:     make sure to know who you are before you are allowed to send mail (and no
  359:     spam), you need to run `fetchmail` again first.
  360:  4. Write the command `/usr/sbin/postfix flush` to transfer the queued
  361:     messages to the provider.
  362:  5. Deactivate the connection when the queue is empty.
  363: 
  364: ## Advanced mail tools
  365: 
  366: When you start using mail, you won't probably have very sophisticated
  367: requirements and the already described standard configuration will satisfy all
  368: your needs. But for many users the number of daily messages will increase with
  369: time and a more rational organization of the mail storage will become necessary,
  370: for example subdividing mail in different mail boxes organized by topic. If, for
  371: example, you subscribe to a mailing list, you will likely receive many
  372: messages every day and you will want to keep them separate from the rest of
  373: your mail. You will soon find that you are spending too much time every day
  374: repeating the same manual operations to organize your mail boxes.
  375: 
  376: Why repeat the same operations manually when you can have a program perform them
  377: automatically for you? There are numerous tools that you can add to your mail
  378: system to increase its flexibility and automatically process your messages.
  379: Amongst the most known and used there are:
  380: 
  381:  * *procmail*, an advanced mail delivery agent and general purpose mail filter
  382:    for local mail, which automatically processes incoming mail using user
  383:    defined rulesets. It integrates smoothly with sendmail/postfix.
  384:  * *spamassassin* or *spamprobe*, to help fight spam.
  385:  * *metamail*, a tool to process attachments.
  386:  * *formail*, a mail formatter.
  387: 
  388: In the remaining part of this section a sample configuration for procmail will
  389: be presented for a very common case: delivering automatically to a user defined
  390: mailbox all the messages coming from a mailing list. The configuration of
  391: postfix will be modified in order to call procmail directly (procmail will be
  392: the *local mailer* used by sendmail). and a custom configuration file for
  393: procmail will be created.
  394: 
  395: First, procmail must be installed using the package system (`mail/procmail`),
  396: `pkg_add` or `pkgin`.
  397: 
  398: Next, the configuration of postfix must be changed, in order to use procmail as
  399: local mailer:
  400: 
  401:     mailbox_command = /usr/pkg/bin/procmail
  402: 
  403: The line defines the path of the procmail program (you can see where procmail is
  404: installed with the command `which procmail`).
  405: 
  406: The last step is the creation of the procmail configuration file, containing the
  407: recipes for mail delivery.
  408: 
  409: Let's say that, for example, you subscribed to a mailing list on roses whose
  410: address is `roses@flowers.org` and that every message from the list contains the
  411: following line in the header:
  412: 
  413:     Delivered-To: roses@flowers.org
  414: 
  415: Assuming you want to automatically sort all mails going over that list into the
  416: local mail folder `roses_list`, the procmail configuration file (`.procmailrc`)
  417: looks like this:
  418: 
  419:     PATH=/bin:/usr/bin:/usr/pkg/bin
  420:     MAILDIR=$HOME/Mail
  421:     LOGFILE=$MAILDIR/from
  422:     
  423:     :0
  424:     * ^Delivered-To: roses@flowers.org
  425:     roses_list
  426: 
  427: The previous file contains only one rule, beginning with the line containing
  428: `:0`. The following line identifies all messages containing the string
  429: `Delivered-To: roses@flowers.org` and the last line says that the selected
  430: messages must go to the `roses_list` mailbox (which you should have created in
  431: $MAILDIR). The remaining messages will be delivered to the default mailbox. Note
  432: that $MAILDIR is the same directory that you have configured with mutt:
  433: 
  434:     set folder="~/Mail"
  435: 
  436: Of course the mailing list is only an example; procmail is a very versatile tool
  437: which can be used to filter mail based on many criteria. As usual, refer to the
  438: man pages for more details:
  439: [[!template id=man name="procmail" section="1"]],
  440: [[!template id=man name="procmailrc" section="5"]],
  441: and
  442: [[!template id=man name="procmailex" section="5"]]
  443: (this last one contains many examples of configuration files).
  444: 
  445: ## News with tin
  446: 
  447: The word *news* indicates the set of messages posted to the USENET newsgroups, a
  448: service available on the Internet. Each newsgroup contains articles related to a
  449: specific topic. Reading a newsgroup is different than reading a mailing list:
  450: when you subscribe to a mailing list you receive the articles by mail and you
  451: read them with a standard mail program like mutt, which you use also to send
  452: replies. News, instead, are read directly from a news server with a dedicated
  453: program called *newsreader* like, for example, tin. With tin you can subscribe
  454: to the newsgroups that you're interested in and follow the *threads*. A thread
  455: is a sequence of articles which all derive from an article that we could call
  456: *original*. In short, a message is sent to the group, someone answers, other
  457: people answer to those who answered in the first place and so on, creating a
  458: tree like structure of messages and replies: without a newsreader it is
  459: impossible to understand the correct sequence of messages.
  460: 
  461: After the installation of tin (from the package collection as usual) the only
  462: thing left to do is to write the name of the NNTP server in the file
  463: `/usr/pkg/etc/nntp/server`, which you may need to create first. For example:
  464: 
  465:     news.bignet.it
  466: 
  467: Once this has been done, the program can be started with the command `tin`. On
  468: the screen something similar to the following example will be displayed:
  469: 
  470:     $ tin
  471:     Connecting to news.bignet.it...
  472:     news.bignet.it InterNetNews NNRP server INN 1.7.2 08-Dec-1997 ready (posting ok).
  473:     Reading groups from active file...
  474:     Checking for new groups...
  475:     Reading attributes file...
  476:     Reading newsgroups file...
  477:     Creating newsrc file...
  478:     Autosubscribing groups...
  479:     Reading newsrc file...
  480: 
  481: Be patient when you connect for the first time, because tin downloads an immense
  482: list of newsgroups to which you can subscribe and this takes several minutes.
  483: When the download is finished, the program's main screen is displayed; usually
  484: no groups are displayed; to see the list of groups press `y`. To subscribe to a
  485: group, move on the group's name and press `y`.
  486: 
  487: Once that you have subscribed to some newsgroups you can start tin more quickly
  488: with the command `tin -Q`. The search for new groups is disabled (`-q`), only
  489: active groups are searched (`-n`) and newsgroup description are not loaded
  490: (`-d`): it will not be possible to use the `y` (yank) command in tin. When tin
  491: is started with this option it can't tell if a newsgroup is moderated or not.
  492: 
  493: Note that if you are connecting from an internal network (like in our example),
  494: when you send ("post") a message the address at the beginning of the message
  495: will be wrong (because it is the internal address). To solve the problem, use
  496: the option `mail_address` in the tin configuration file (`~/.tin/tinrc`) or set
  497: the `REPLYTO` environment variable.
  498: 

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