  The Linux Mail User HOWTO
  Eric S. Raymond, <esr@thyrsus.com>
  v2.2, 07 May 1999

  This document is an introduction to the world of electronic mail
  (email) under Linux. It focuses on user-level issues and typical con-
  figurations for Linux home and small-business machines connected to
  the net via an ISP.  You need to read this if you plan to communicate
  locally or to remote sites via electronic mail.  You probably do not
  need to read this document if don't exchange electronic mail with
  other users on your system or with other sites.  For information on
  configuring and administering mail, see the Mail Administrator HOWTO.
  ______________________________________________________________________

  Table of Contents


  1. Introduction

     1.1 New versions of this document
     1.2 Hardware requirements for email programs
     1.3 Software sources for email programs

  2. Mail User Agents

     2.1 Setting your mail editor
     2.2 mutt
     2.3 elm
     2.4 pine
     2.5 Netscape
     2.6 Emacs rmail/smail and vm.
     2.7 BSD mail
     2.8 Other user agents

  3. Advanced topics

     3.1 Aliases
     3.2 Forwarding
     3.3 Auto-answering
     3.4 Mailing lists
     3.5 Mail filters
     3.6 Coping with spam

  4. Other sources of information

     4.1 USENET
     4.2 Books
     4.3 Periodic USENET Postings
     4.4 Where

  5. Administrivia

     5.1 Feedback
     5.2 Copyright Information
     5.3 Standard Disclaimer
     5.4 Acknowledgements


  ______________________________________________________________________

  1.  Introduction

  The intent of this document is to explain how email works, and answer
  some of the questions that appear to meet the definition of
  `frequently asked questions' about e-mail software under Linux.

  Modern Linux distributions give you a usable, preconfigured setup for
  electronic mail out of the box, usually featuring a late version of
  sendmail-v8.  This HOWTO will assume that you have such a setup and a
  working Internet connection.

  (For information on how to set up a PPP or SLIP link to an ISP, see
  the ISP Hookup HOWTO <http://metalab.unc.edu/LDP/HOWTO/ISP-Hookup-
  HOWTO.html>.)

  Accordingly, unlike Vince Skahan's 1.x versions, this HOWTO focuses on
  user issues and architecture; most technical hair about UUCP, IDA
  sendmail and other formerly important topics has been dropped.


  1.1.  New versions of this document

  This document will be posted monthly to the newsgroup
  comp.os.linux.answers <news:comp.os.linux.answers> You should also be
  able to view the latest version of this HOWTO on the World Wide Web at
  <http://metalab.unc.edu/LDP/HOWTO/Mail-User-HOWTO.html>.


  1.2.  Hardware requirements for email programs

  There are no specific hardware requirements for mail under Linux.  If
  you have the hardware necessary to connect to the Internet, it can
  support email over that link.


  1.3.  Software sources for email programs

  The software you will need for email support is probably preinstalled
  in your Linux distribution.  You will find updates on the Metalab
  Linux Archive <http://metalab.unc.edu/pub/Linux>, especially in the
  mail subdirectory <http://metalab.unc.edu/pub/Linux/system/mail>.


  2.  Mail User Agents

  This section contains information related to user agents, which means
  the software the user sees and uses.  This software relies on the
  transport agents described in the Mail Administrator's HOWTO (which
  also include user=agent configuration and troubleshooting tips for
  administrators).


  2.1.  Setting your mail editor

  Mail user agents call out to some editor to assist composition of
  mail.  Which editor is the default varies.  Most of them respect a
  convention going back to Unix's early days; the contents of the
  environment variable VISUAL, if it exists, is taken as the name of
  your preferred editor.  If VISUAL is not set, the variable EDITOR is
  checked.

  Popular values for EDITOR include `vi' and `emacs'.  But if you are,
  like me, the sort who always has an Emacs running, the most useful way
  to set EDITOR is to the value `emacsclient'.  Use this with the
  following lines in your .emacs file:


  ______________________________________________________________________
  (autoload 'server-edit "server" nil t)
  (server-edit)
  ______________________________________________________________________

  The emacsclient program, when it runs, tries to establish
  communication with an Emacs instance you already have running and hand
  the mail message temporary file to that Emacs to be edited.  The
  effect of this will be that when your mailer calls out for an editor,
  a mail composition window pops open inside your Emacs.

  When you are ready to hand the file back to the mailer for sending,
  type C-x #.  The mail buffer will leave your display and the
  emacsclient instance your mailer called will return, handing control
  back to the mailer.

  It is possible to have more than one emacsclient instance open at once
  without confusing Emacs.  However, calling up another Emacs while an
  emacsclient session is running can confuse emacsclient enough that it
  won't be able to find either instance afterwards.  If this happens,
  shut down all your Emacs instances and restart just one.


  2.2.  mutt

  This is what I use and recommend.  It is descended from elm and has
  similar commands by default, but is much more powerful and
  configurable.  It can be a POP3 or IMAP client, and includes excellent
  support for MIME and PGP.  There is a Mutt home page at
  http://www.mutt.org <http://www.mutt.org>.

  Mutt respects the EDITOR/VISUAL convention.


  2.3.  elm

  Elm was the first modern, screen-oriented Unix mailer, but has been
  stagnant for years now and is being displaced by Mutt.  Some versions
  of elm have POP3 support built in. For more information, see the elm
  sources and installation instructions in the Metalab mail user agents
  directory <http://metalab.unc.edu/pub/Linux/system/mail>.  Here are a
  few points that occasionally trip people up:

  No, stock elm is not PGP-aware.  There are PGP support patches, but
  Mutt's PGP support is superior.  If you want to use PGP, I recommend
  Mutt.

  Elm respects the EDITOR/VISUAL convention.


  2.4.  pine

  Pine is a user agent designed for novices; it includes news-reading
  capability and built-in support for the IMAP remote-mail protocol.  A
  lot of people swear by it for new users.  I find its impoverished
  command set, limited configurability and native editor hard to take.
  It has excellent built-in IMAP support, however.  If you want to check
  it out, the distribution is available at
  http://www.washington.edu/pine <http://www.washington.edu/pine>.

  Pine respects the EDITOR/VISUAL convention.


  2.5.  Netscape

  The Netscape browser has POP3 and IMAP remote-mail capability built
  into it, so it can be used as a mail user agent.  I don't recommend
  this; it doesn't specialize in being an MUA, and therefore does not
  offer many of the services that real MUAs do (such as aliases and PGP
  handling).

  Neetscape supplies its own mini-editor, the same one used throughout
  the browser (e.g. for text fields in forms).


  2.6.  Emacs rmail/smail and vm.

  Emacs has a mode called smail that can send mail, and another called
  rmail that can read mail.  The smail mode can be quite useful, as you
  get to compose mail inside a full Emacs environment (but see also the
  discussion of ``emacsclient'' elsewhere in this document).

  The rmail mode, on the other hand, is not recommended.  Every time you
  run it, it converts your inbox to BABYL format; ordinary mail tools
  will choke on that.  (If this happens to you, do M-x unrmail from the
  Emacs command line.)

  There is a mailreader for emacs called `vm' that writes and reads
  standard V7 mailboxes.  It is not distributed with GNU Emacs, but you
  can find its home page at http://www.wonderworks.com/vm/
  <http://www.wonderworks.com/vm/>.

  Emacs smail/rmail/vm do not respect the EDITOR/VISUAL convention.
  Instead, you use the Emacs they're embedded in.


  2.7.  BSD mail

  If you simply type `mail' to the shell on a Linux or any other modern
  Unix, you will invoke some variant of the BSD Mail program.  It has a
  line-oriented interface originally designed for use on TTYs.  It is,
  at this point, only of historical interest.

  BSD Mail invented the EDITOR/VISUAL convention.


  2.8.  Other user agents

  The following also are known to run under Linux.  Consult `archie' to
  find them...

  o  mush      - mail user's shell, very powerful for filtering and
     batch processing

  o  mh      - mail handler, yet another mail user agent

  I don't know enough about mh or mush to describe them in detail.  They
  both have rather complex interfaces and are designed for sophisticated
  mail users.


  3.  Advanced topics


  3.1.  Aliases

  An `alias' is a way to set up a pseudo-address that simply directs
  mail to another (single) address.  There are two kinds of aliases: MUA
  aliases and MTA aliases.

  An MUA alias is one you set up in your MUA as a kind of personal
  shorthand.  Other people will not be able to see or use this alias.
  For example, you could write



  ______________________________________________________________________
  alias esr       Eric S. Raymond <esr@thyrsus.com>
  ______________________________________________________________________



  in your mutt configuration file.  This would tell mutt that when it
  sees `esr' in an address line, it should behave as through you had
  typed `esr@thyrsus.com',  Or you can type `mutt esr' and the expanded
  address will be automatically filled in on the `to' line.

  An MTA alias is one your MTA expands; it will be usable by everyone,
  both on your machine and remotely.  To create MTA aliases you must
  modify a system file, usually but not always /etc/aliases (the
  location depends on your MTA).  It may be instructive for you to look
  at the /etc/aliases on your system; it should contain a number of
  standard aliases such as `postmaster'.

  Your MTA may also allow the target of an alias to be a filename, which
  will be treated as a mailbox the mail is to be appended to (this is
  useful for archiving mail).  It may also allow the target of an alias
  to be a program, in which case mail to that alias will be passed to an
  instance of the program on its standard input.


  3.2.  Forwarding

  MTA aliases usually require administrator privileges to set up.  But
  it is desirable for mail users to be able to set up forwarding of
  their own mail without administrator intervention.

  To support this, most MTAs follow sendmail's lead and look for a file
  called .forward in your home directory.  The contents of this file is
  interpreted like the target of an alias which should receive all your
  mail.  The most common use for this facility is to redirect your mail
  to an account on another machine.


  3.3.  Auto-answering

  Another common use for the .forward facility is to pass your mail to a
  `vacation' program.  A vacation program reads incoming mail and
  automatically generates a canned reply to it; they are so called
  because the most common form of canned reply is to inform the sender
  that you are on vacation and will not be reachable until a given date.

  There is no one standard vacation program that is in universal use.
  There are two good reasons for this: one, that such a program is very
  easy to write as a shellscript of filter rule (see below); and two,
  that vacation programs interact badly with mailing lists.

  You should temporarily unsubscribe from all mailing lists you are on
  before setting up auto-answering; otherwise, all members of the
  mailing lists mail find they are being flooded with canned messages by
  your vacation program.  This is considered very rude behavior and will
  guarantee you quite a frosty reception on your return.


  3.4.  Mailing lists

  A mailing list is a pseudo-address that sends mail to more than one
  user.

  In its simplest form, mailing list is just an MTA alias with more than
  one recipient. Some small mailing lists are maintained this way.
  Sendmail assists by supporting a syntax in /etc/aliases that includes
  the contents of a given mailing list file in the target side of an
  alias.  It looks like this:


  ______________________________________________________________________
  admin-list:     ":include:/usr/home/admin/admin-list"
  ______________________________________________________________________



  with the advantage that the admin-list file can live in unprivileged-
  user space somewhere (root is only needed to set up the original
  inclusion). Some other MTAs have similar features.

  These simple lists are commonly called `mail reflectors'.  There are a
  couple of problems with mail reflectors.  One is that bounce messages
  from failed attempts to broadcast goes to all users.  Another is that
  all subscriptions and unsubscriptions have to be done manually by the
  mailing list administrator.

  A kind of software called a mailing list manager has evolved to
  address these problems and other related ones.  Its most important
  function is to permit mailing list users to subscribe and unscubscribe
  without going through the list maintainer.

  A mailing-list manager keeps its own user-list information and hooks
  up to the MTA through a program alias in /etc/aliases.  For example,
  if the admin-list above were going through the mailing list manager
  called SmartList on a sendmail system, a portion of /etc/aliases might
  look like this:


  ______________________________________________________________________
  admin-list: "|/usr/home/smartlist/bin/flist admin-list"
  admin-list-request: "|/usr/home/smartlist/bin/flist admin-list-request"
  ______________________________________________________________________



  Note that this is a pair of aliases.  It is conventional for real
  mailing lists to have a request address to be used for user
  subscription and unsubscription requests.  It is considered rude and
  ignorant to send subscription/unsubscription requests to the main
  address of such a list -- don't do it.

  The robot sitting behind the request address may offer other features
  besides just subscription/unsubscription.  It may respond to help
  requests, allow you to query who is on the list, or give you automated
  access to list archives.  It may also allow list administrators to
  restrict posting to known members, set the list to auto-subscribe
  nonmembers when they first post, or set various security policy
  options.  Mailing-list managers differ primarily in the design and
  range of these secondary features.

  Unfortunately, the format for sending commands to mailing-list request
  robots is not standard.  Some expect commands in the subject line,
  some ignore the subject line and expect commands in the message body.
  You need to pay attention to the response mail you get when you first
  subscribe; it's a good idea to save such mail to a subscriptions
  mailbox for later reference.

  The most important mailing-list managers to know about are majordomo,
  listserv, listproc, and smartlist; majordomo is the most popular by a
  considerable margin.  There is a rather comprehensive list
  <http://www.catalog.com/vivian/mailing-list-software.html> of such
  packages on the Web.
  For more about mailing list managers, consult the resources at the
  List-Managers Mailing List <http://www.greatcircle.com/list-
  managers/>, including the FAQ (note: this list is not appropriate for
  how-to questions).


  3.5.  Mail filters

  A mail filter is a program that sits between your local delivery agent
  and you, automatically dispatching or rejecting mail before you see
  it.

  Mail filters have a number of uses.  The most important are spam
  filtering, dispatching to multiple mailboxes by topic or sender, and
  auto-answering mail.

  Typically, you set up mail filtering by putting a program alias for
  the filter program in your .forward file, and writing a file of
  filtering rules.  The format and location of the filter rules file
  varies between filter programs.

  There are good feature summaries of the three major mail filters
  (procmail, mailagent, and deliver) in part 3
  <http://www.faqs.org/faqs/mail/setup/unix/part3/index.html> of Chris
  Lewis's Email Software Survey.  The most popular of these is (despite
  its rather nasty rule syntax) procmail, which is universally present
  on Linux systems (and, indeed, is generally used as the system's local
  delivery agent).


  3.6.  Coping with spam

  Spam is sometimes known as `UCE' (Unsolicited Commercial Email) or
  `UBE' (Unsolicited Bulk Email).  As these names imply, it is an
  obnoxious form of advertising that stuffs your mailbox with form
  letters.  (The term `spam' comes from a Monty Python's Flying Circus
  skit in which a choir of Vikings endlessly repeats the chant "Spam
  spam spam spam...").

  Most spam seems to consist of solicitations for pyramid schemes, ads
  for pornography, or (annoyingly) attempts to sell spam-sending
  programs.  A few individual spams (like MAKE MONEY FAST or the Craig
  Shergold postcard hoax) have been so persistent as to become
  legendary.  Spam tends to be both verbose and illiterate.  It's a
  waste of time and a huge waste of network bandwidth.

  The spam epidemic seems to have peaked in mid-1997 and been slowly in
  decline since, but it can still be a serious annoyance.  If you're
  being deluged with spam, get educated.  Browse the Fight Spam on the
  Internet! <http://spam.abuse.net/> page.  The Death To Spam!
  <http://www.mindworkshop.com/alchemy/nospam.html> page is particularly
  effective on methods  for stopping or backtracking spam.


  4.  Other sources of information



  4.1.  USENET

  There are a number of Usenet groups devoted to electronic-mail
  technical issues:


  o  comp.mail.elm the ELM mail system.

  o  comp.mail.mh The Rand Message Handling system.

  o  comp.mail.mime Multipurpose Internet Mail Extensions.

  o  comp.mail.misc General discussions about computer mail.

  o  comp.mail.multi-media Multimedia Mail.

  o  comp.mail.mush The Mail User's Shell (MUSH).

  o  comp.mail.sendmail the BSD sendmail agent.

  o  comp.mail.smail the smail mail agent.

  o  comp.mail.uucp Mail in the uucp environment.


  4.2.  Books


  The following is a non-inclusive set of books that will help...


  o  ``Sendmail" from O'Reilly and Associates is the definitive
     reference on sendmail-v8 and sendmail+IDA.  It's a ``must have''
     for anybody hoping to make sense out of sendmail without bleeding
     in the process.

  o  "The Internet Complete Reference" from Osborne is a fine reference
     book that explains the various services available on Internet and
     is a great source for information on news, mail, and various other
     Internet resources.

  o  "The Linux Networking Administrators' Guide" from Olaf Kirch of the
     LDP is available on the net and is also published by (at least)
     O'Reilly and SSC.  It makes a fine one-stop shopping guide to learn
     about everything you ever imagined you'd need to know about Unix
     networking.


  4.3.  Periodic USENET Postings

  Also worth mentioning, is Chris Lewis' periodic posting on unix e-mail
  software, which is available on
  <ftp://rtfm.mit.edu/pub/usenet/comp.mail.misc> as the files named
  ``UNIX_Email_Software_Survey_*''.  An HTMLized version is at
  http://www.faqs.org/faqs/mail/setup/unix/
  <http://www.faqs.org/faqs/mail/setup/unix/>.  At time writing in 1999
  this posting has not been seriously updated since 1996, however.


  4.4.  Where NOT  to look for help

  There is no longer anything special about configuring and running mail
  under Linux, relative to other Unixes.  Accordingly, you almost
  certainly do NOT want to be posting generic mail-related questions to
  the comp.os.linux.* newsgroups.

  Unless your posting is truly Linux-specific (ie, ``please tell me what
  routers are already compiled into the SLS1.03 version of
  smail3.1.28'') you should be asking your questions in one of the
  newsgroups or mailing lists referenced above.

  Let me repeat that.


  There is virtually no reason to post anything mail-related in the
  comp.os.linux hierarchy any more.  There are existing newsgroups in
  the comp.mail.* hierarchy to handle ALL your questions.

  If you post to comp.os.linux.* for non-Linux-specific questions, you
  are looking in the wrong place for help.  The electronic mail experts
  hang out in the places indicated above and generally not in the Linux
  groups.

  Posting to the Linux hierarchy for non-linux-specific questions wastes
  your time and everybody else's...and it frequently delays you from
  getting the answer to your question.


  5.  Administrivia


  5.1.  Feedback


  (Vince wrote this section, but my policy is the same.)

  I am interested in any feedback, positive or negative, regarding the
  content of this document via e-mail.  Definitely contact me if you
  find errors or obvious omissions.

  I read, but do not necessarily respond to, all e-mail I receive.
  Requests for enhancements will be considered and acted upon based on
  that day's combination of available time, merit of the request, and
  daily blood pressure :-)

  Flames will quietly go to /dev/null so don't bother.

  In particular, the Linux filesystem standard for pathnames is an
  evolving thing.  What's in this document is there for illustration
  only based on the current standard at the time that part of the
  document was written and in the paths used in the distributions or
  `kits' I've personally seen.  Please consult your particular Linux
  distribution(s) for the paths they use.

  Feedback concerning the actual format of the document should go to the
  HOWTO coordinator - mail to linux-howto@metalab.unc.edu <mailto:linux-
  howto@metalab.unc.edu>).


  5.2.  Copyright Information


  The Mail-HOWTO is copyrighted (c)1999 Eric S. Raymond.  Copyright is
  retained for the purpose of enforcing the Linux Documentation Project
  license terms.

  A verbatim copy may be reproduced or distributed in any medium
  physical or electronic without permission of the author.  Translations
  are similarly permitted without express permission if it includes a
  notice on who translated it.

  Short quotes may be used without prior consent by the author.
  Derivative work and partial distributions of the Mail-HOWTO must be
  accompanied with either a verbatim copy of this file or a pointer to
  the verbatim copy.

  Commercial redistribution is allowed and encouraged; however, the
  maintainer would appreciate being notified of any such distributions
  (as a courtesy).

  In short, we wish to promote dissemination of this information through
  as many channels as possible. However, we do wish to retain copyright
  on the HOWTO documents.

  We further want that all information provided in the HOWTOS is
  disseminated.  If you have questions, please contact the Linux HOWTO
  coordinator, at linux-howto@metalab.unc.edu.


  5.3.  Standard Disclaimer


  Of course, we disavow any potential liability for the contents of this
  document.  Use of the concepts, examples, and/or other content of this
  document is entirely at your own risk.


  5.4.  Acknowledgements

  This was originally authored by Vince Skahan.  I have rewritten it for
  the modern ISP-centric world in which UUCP is little more than a
  memory.

  In May 1999, the name was changed from "The Linux Electronic Mail
  HOWTO" to avoid a collision with Guylhem Aznar's Mail HOWTO, which
  will become the Mail Administrator HOWTO.



