<?xml version="1.0" encoding="iso-8859-1"?>
<!--
The FreeBSD Documentation Project
$FreeBSD$
-->
<chapter id="mail">
<chapterinfo>
<authorgroup>
<author>
<firstname>Bill</firstname>
<surname>Lloyd</surname>
<contrib>Original work by </contrib>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Jim</firstname>
<surname>Mock</surname>
<contrib>Rewritten by </contrib>
<!-- 2 Dec 1999 -->
</author>
</authorgroup>
</chapterinfo>
<title>Electronic Mail</title>
<sect1 id="mail-synopsis">
<title>Synopsis</title>
<indexterm><primary>email</primary></indexterm>
<para><quote>Electronic Mail</quote>, better known as email, is one of the
most widely used forms of communication today. This chapter provides
a basic introduction to running a mail server on &os;, as well as an
introduction to sending and receiving email using &os;; however,
it is not a complete reference and in fact many important
considerations are omitted. For more complete coverage of the
subject, the reader is referred to the many excellent books listed
in <xref linkend="bibliography"/>.</para>
<para>After reading this chapter, you will know:</para>
<itemizedlist>
<listitem>
<para>What software components are involved in sending and receiving
electronic mail.</para>
</listitem>
<listitem>
<para>Where basic <application>sendmail</application> configuration
files are located in FreeBSD.</para>
</listitem>
<listitem>
<para>The difference between remote and
local mailboxes.</para>
</listitem>
<listitem>
<para>How to block spammers from illegally using your mail server as a
relay.</para>
</listitem>
<listitem>
<para>How to install and configure an alternate Mail Transfer Agent on
your system, replacing <application>sendmail</application>.</para>
</listitem>
<listitem>
<para>How to troubleshoot common mail server problems.</para>
</listitem>
<listitem>
<para>How to use SMTP with UUCP.</para>
</listitem>
<listitem>
<para>How to set up the system to send mail only.</para>
</listitem>
<listitem>
<para>How to use mail with a dialup connection.</para>
</listitem>
<listitem>
<para>How to configure SMTP Authentication for added security.</para>
</listitem>
<listitem>
<para>How to install and use a Mail User Agent, such as
<application>mutt</application> to send and receive email.</para>
</listitem>
<listitem>
<para>How to download your mail from a remote <acronym>POP</acronym>
or <acronym>IMAP</acronym> server.</para>
</listitem>
<listitem>
<para>How to automatically apply filters and rules to incoming
email.</para>
</listitem>
</itemizedlist>
<para>Before reading this chapter, you should:</para>
<itemizedlist>
<listitem>
<para>Properly set up your network connection
(<xref linkend="advanced-networking"/>).</para>
</listitem>
<listitem>
<para>Properly set up the DNS information for your mail host
(<xref linkend="network-servers"/>).</para>
</listitem>
<listitem>
<para>Know how to install additional third-party software
(<xref linkend="ports"/>).</para></listitem>
</itemizedlist>
</sect1>
<sect1 id="mail-using">
<title>Using Electronic Mail</title>
<indexterm><primary>POP</primary></indexterm>
<indexterm><primary>IMAP</primary></indexterm>
<indexterm><primary>DNS</primary></indexterm>
<para>There are five major parts involved in an email exchange. They
are: <link linkend="mail-mua">the user program</link>, <link
linkend="mail-mta">the server daemon</link>, <link
linkend="mail-dns">DNS</link>, <link linkend="mail-receive">a
remote or local mailbox</link>, and of course, <link linkend="mail-host">the
mailhost itself</link>.</para>
<sect2 id="mail-mua">
<title>The User Program</title>
<para>This includes command line programs such as
<application>mutt</application>,
<application>alpine</application>, <application>elm</application>,
and <command>mail</command>, and <acronym>GUI</acronym> programs such as
<application>balsa</application>,
<application>xfmail</application> to name a few, and something
more <quote>sophisticated</quote> like a WWW browser. These
programs simply pass off the email transactions to the local
<link linkend="mail-host"><quote>mailhost</quote></link>, either
by calling one of the <link linkend="mail-mta">server
daemons</link> available, or delivering it over <acronym>TCP</acronym>.</para>
</sect2>
<sect2 id="mail-mta">
<title>Mailhost Server Daemon</title>
<indexterm>
<primary>mail server daemons</primary>
<secondary><application>sendmail</application></secondary>
</indexterm>
<indexterm>
<primary>mail server daemons</primary>
<secondary><application>postfix</application></secondary>
</indexterm>
<indexterm>
<primary>mail server daemons</primary>
<secondary><application>qmail</application></secondary>
</indexterm>
<indexterm>
<primary>mail server daemons</primary>
<secondary><application>exim</application></secondary>
</indexterm>
<para>&os; ships with <application>sendmail</application> by
default, but also support numerous other mail server daemons,
just some of which include:</para>
<itemizedlist>
<listitem>
<para><application>exim</application>;</para>
</listitem>
<listitem>
<para><application>postfix</application>;</para>
</listitem>
<listitem>
<para><application>qmail</application>.</para>
</listitem>
</itemizedlist>
<para>The server daemon usually has two functions—it is responsible
for receiving incoming mail as well as delivering outgoing mail. It is
<emphasis>not</emphasis> responsible for the collection of mail using protocols
such as <acronym>POP</acronym> or <acronym>IMAP</acronym> to
read your email, nor does it allow connecting to local
<filename>mbox</filename> or Maildir mailboxes. You may require
an additional <link linkend="mail-receive">daemon</link> for
that.</para>
<warning>
<para>Older versions of <application>sendmail</application>
have some serious security issues which may result in an
attacker gaining local and/or remote access to your machine.
Make sure that you are running a current version to avoid
these problems. Optionally, install an alternative
<acronym>MTA</acronym> from the <link linkend="ports">&os;
Ports Collection</link>.</para>
</warning>
</sect2>
<sect2 id="mail-dns">
<title>Email and DNS</title>
<para>The Domain Name System (DNS) and its daemon
<command>named</command> play a large role in the delivery of
email. In order to deliver mail from your site to another, the
server daemon will look up the remote site in the DNS to determine the
host that will receive mail for the destination. This process
also occurs when mail is sent from a remote host to your mail
server.</para>
<indexterm>
<primary>MX record</primary>
</indexterm>
<para><acronym>DNS</acronym> is responsible for mapping
hostnames to IP addresses, as well as for storing information
specific to mail delivery, known as MX records. The MX (Mail
eXchanger) record specifies which host, or hosts, will receive
mail for a particular domain. If you do not have an MX record
for your hostname or domain, the mail will be delivered
directly to your host provided you have an A record pointing
your hostname to your IP address.</para>
<para>You may view the MX records for any domain by using the
&man.host.1; command, as seen in the example below:</para>
<screen>&prompt.user; <userinput>host -t mx FreeBSD.org</userinput>
FreeBSD.org mail is handled (pri=10) by mx1.FreeBSD.org</screen>
</sect2>
<sect2 id="mail-receive">
<title>Receiving Mail</title>
<indexterm>
<primary>email</primary>
<secondary>receiving</secondary>
</indexterm>
<para>Receiving mail for your domain is done by the mail host. It
will collect all mail sent to your domain and store it
either in <filename>mbox</filename> (the default method for storing mail) or Maildir format, depending
on your configuration.
Once mail has been stored, it may either be read locally using
applications such as &man.mail.1; or
<application>mutt</application>, or remotely accessed and
collected using protocols such as
<acronym>POP</acronym> or <acronym>IMAP</acronym>.
This means that should you only
wish to read mail locally, you are not required to install a
<acronym>POP</acronym> or <acronym>IMAP</acronym> server.</para>
<sect3 id="pop-and-imap">
<title>Accessing remote mailboxes using <acronym>POP</acronym> and <acronym>IMAP</acronym></title>
<indexterm><primary>POP</primary></indexterm>
<indexterm><primary>IMAP</primary></indexterm>
<para>In order to access mailboxes remotely, you are required to
have access to a <acronym>POP</acronym> or <acronym>IMAP</acronym>
server. These protocols allow users to connect to their mailboxes from
remote locations with ease. Though both
<acronym>POP</acronym> and <acronym>IMAP</acronym> allow users
to remotely access mailboxes, <acronym>IMAP</acronym> offers
many advantages, some of which are:</para>
<itemizedlist>
<listitem>
<para><acronym>IMAP</acronym> can store messages on a remote
server as well as fetch them.</para>
</listitem>
<listitem>
<para><acronym>IMAP</acronym> supports concurrent updates.</para>
</listitem>
<listitem>
<para><acronym>IMAP</acronym> can be extremely useful over
low-speed links as it allows users to fetch the structure
of messages without downloading them; it can also
perform tasks such as searching on the server in
order to minimize data transfer between clients and
servers.</para>
</listitem>
</itemizedlist>
<para>In order to install a <acronym>POP</acronym> or
<acronym>IMAP</acronym> server, the following steps should be
performed:</para>
<procedure>
<step>
<para>Choose an <acronym>IMAP</acronym> or
<acronym>POP</acronym> server that best suits your needs.
The following <acronym>POP</acronym> and
<acronym>IMAP</acronym> servers are well known and serve
as some good examples:</para>
<itemizedlist>
<listitem>
<para><application>qpopper</application>;</para>
</listitem>
<listitem>
<para><application>teapop</application>;</para>
</listitem>
<listitem>
<para><application>imap-uw</application>;</para>
</listitem>
<listitem>
<para><application>courier-imap</application>;</para>
</listitem>
<listitem>
<para><application>dovecot</application>;</para>
</listitem>
</itemizedlist>
</step>
<step>
<para>Install the <acronym>POP</acronym> or
<acronym>IMAP</acronym> daemon of your choosing from the
ports
collection.</para>
</step>
<step>
<para>Where required, modify <filename>/etc/inetd.conf</filename>
to load the <acronym>POP</acronym> or
<acronym>IMAP</acronym> server.</para>
</step>
</procedure>
<warning>
<para>It should be noted that both <acronym>POP</acronym> and
<acronym>IMAP</acronym> transmit information, including
username and password credentials in clear-text. This means
that if you wish to secure the transmission of information
across these protocols, you should consider tunneling
sessions over &man.ssh.1; or using SSL. Tunneling sessions is
described in <xref linkend="security-ssh-tunneling"/> and SSL is
described in <xref linkend="openssl"/>.</para>
</warning>
</sect3>
<sect3 id="local">
<title>Accessing Local Mailboxes</title>
<para>Mailboxes may be accessed locally by directly utilizing
<acronym>MUA</acronym>s on the server on which the mailbox
resides. This can be done using applications such as
<application>mutt</application> or &man.mail.1;.
</para>
</sect3>
</sect2>
<sect2 id="mail-host">
<title>The Mail Host</title>
<indexterm><primary>mail host</primary></indexterm>
<para>The mail host is the name given to a server that is
responsible for delivering and receiving mail for your host, and
possibly your network.</para>
</sect2>
</sect1>
<sect1 id="sendmail">
<sect1info>
<authorgroup>
<author>
<firstname>Christopher</firstname>
<surname>Shumway</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title><application>sendmail</application> Configuration</title>
<indexterm>
<primary><application>sendmail</application></primary>
</indexterm>
<para>&man.sendmail.8; is the default Mail Transfer Agent (MTA) in
FreeBSD. <application>sendmail</application>'s job is to accept
mail from Mail User Agents (<acronym>MUA</acronym>) and deliver it
to the appropriate mailer as defined by its configuration file.
<application>sendmail</application> can also accept network
connections and deliver mail to local mailboxes or deliver it to
another program.</para>
<para><application>sendmail</application> uses the following
configuration files:</para>
<indexterm>
<primary><filename>/etc/mail/access</filename></primary>
</indexterm>
<indexterm>
<primary><filename>/etc/mail/aliases</filename></primary>
</indexterm>
<indexterm>
<primary><filename>/etc/mail/local-host-names</filename></primary>
</indexterm>
<indexterm>
<primary><filename>/etc/mail/mailer.conf</filename></primary>
</indexterm>
<indexterm>
<primary><filename>/etc/mail/mailertable</filename></primary>
</indexterm>
<indexterm>
<primary><filename>/etc/mail/sendmail.cf</filename></primary>
</indexterm>
<indexterm>
<primary><filename>/etc/mail/virtusertable</filename></primary>
</indexterm>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<thead>
<row>
<entry>Filename</entry>
<entry>Function</entry>
</row>
</thead>
<tbody>
<row>
<entry>
<filename>/etc/mail/access</filename>
</entry>
<entry><application>sendmail</application> access database
file</entry>
</row>
<row>
<entry>
<filename>/etc/mail/aliases</filename>
</entry>
<entry>Mailbox aliases</entry>
</row>
<row>
<entry>
<filename>/etc/mail/local-host-names</filename>
</entry>
<entry>Lists of hosts <application>sendmail</application>
accepts mail for</entry>
</row>
<row>
<entry>
<filename>/etc/mail/mailer.conf</filename>
</entry>
<entry>Mailer program configuration</entry>
</row>
<row>
<entry>
<filename>/etc/mail/mailertable</filename>
</entry>
<entry>Mailer delivery table</entry>
</row>
<row>
<entry>
<filename>/etc/mail/sendmail.cf</filename>
</entry>
<entry><application>sendmail</application> master
configuration file</entry>
</row>
<row>
<entry>
<filename>/etc/mail/virtusertable</filename>
</entry>
<entry>Virtual users and domain tables</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<sect2>
<title><filename>/etc/mail/access</filename></title>
<para>The access database defines what host(s) or IP addresses
have access to the local mail server and what kind of access
they have. Hosts can be listed as <option>OK</option>,
<option>REJECT</option>, <option>RELAY</option> or simply passed
to <application>sendmail</application>'s error handling routine with a given mailer error.
Hosts that are listed as <option>OK</option>, which is the
default, are allowed to send mail to this host as long as the
mail's final destination is the local machine. Hosts that are
listed as <option>REJECT</option> are rejected for all mail
connections. Hosts that have the <option>RELAY</option> option
for their hostname are allowed to send mail for any destination
through this mail server.</para>
<example>
<title>Configuring the <application>sendmail</application>
Access Database</title>
<programlisting>cyberspammer.com 550 We do not accept mail from spammers
FREE.STEALTH.MAILER@ 550 We do not accept mail from spammers
another.source.of.spam REJECT
okay.cyberspammer.com OK
128.32 RELAY</programlisting>
</example>
<para>In this example we have five entries. Mail senders that
match the left hand side of the table are affected by the action
on the right side of the table. The first two examples give an
error code to <application>sendmail</application>'s error
handling routine. The message is printed to the remote host when
a mail matches the left hand side of the table. The next entry
rejects mail from a specific host on the Internet,
<hostid>another.source.of.spam</hostid>. The next entry accepts
mail connections from a host
<hostid role="fqdn">okay.cyberspammer.com</hostid>, which is more exact than
the <hostid role="domainname">cyberspammer.com</hostid> line above. More specific
matches override less exact matches. The last entry allows
relaying of electronic mail from hosts with an IP address that
begins with <hostid>128.32</hostid>. These hosts would be able
to send mail through this mail server that are destined for other
mail servers.</para>
<para>When this file is updated, you need to run
<command>make</command> in <filename>/etc/mail/</filename> to
update the database.</para>
</sect2>
<sect2>
<title><filename>/etc/mail/aliases</filename></title>
<para>The aliases database contains a list of virtual mailboxes
that are expanded to other user(s), files, programs or other
aliases. Here are a few examples that can be used in
<filename>/etc/mail/aliases</filename>:</para>
<example>
<title>Mail Aliases</title>
<programlisting>root: localuser
ftp-bugs: joe,eric,paul
bit.bucket: /dev/null
procmail: "|/usr/local/bin/procmail"</programlisting>
</example>
<para>The file format is simple; the mailbox name on the left
side of the colon is expanded to the target(s) on the right.
The
first example expands the mailbox <username>root</username>
to the mailbox <username>localuser</username>, which is then
looked up again in the aliases database. If no match is found,
then the message is delivered to the local user
<username>localuser</username>. The next example shows a mail
list. Mail to the mailbox <username>ftp-bugs</username> is
expanded to the three local mailboxes <username>joe</username>,
<username>eric</username>, and <username>paul</username>. Note
that a remote mailbox could be specified as <email>user@example.com</email>. The
next example shows writing mail to a file, in this case
<filename>/dev/null</filename>. The last example shows sending
mail to a program, in this case the mail message is written to the
standard input of <filename>/usr/local/bin/procmail</filename>
through a &unix; pipe.</para>
<para>When this file is updated, you need to run
<command>make</command> in <filename>/etc/mail/</filename> to
update the database.</para>
</sect2>
<sect2>
<title><filename>/etc/mail/local-host-names</filename></title>
<para>This is a list of hostnames &man.sendmail.8; is to accept as
the local host name. Place any domains or hosts that
<application>sendmail</application> is to be receiving mail for.
For example, if this mail server was to accept mail for the
domain <hostid role="domainname">example.com</hostid> and the host
<hostid role="fqdn">mail.example.com</hostid>, its
<filename>local-host-names</filename> might look something like
this:</para>
<programlisting>example.com
mail.example.com</programlisting>
<para>When this file is updated, &man.sendmail.8; needs to be
restarted to read the changes.</para>
</sect2>
<sect2>
<title><filename>/etc/mail/sendmail.cf</filename></title>
<para><application>sendmail</application>'s master configuration
file, <filename>sendmail.cf</filename> controls the overall
behavior of <application>sendmail</application>, including everything
from rewriting e-mail addresses to printing rejection messages to
remote mail servers. Naturally, with such a diverse role, this
configuration file is quite complex and its details are a bit
out of the scope of this section. Fortunately, this file rarely
needs to be changed for standard mail servers.</para>
<para>The master <application>sendmail</application> configuration
file can be built from &man.m4.1; macros that define the features
and behavior of <application>sendmail</application>. Please see
<filename>/usr/src/contrib/sendmail/cf/README</filename> for
some of the details.</para>
<para>When changes to this file are made,
<application>sendmail</application> needs to be restarted for
the changes to take effect.</para>
</sect2>
<sect2>
<title><filename>/etc/mail/virtusertable</filename></title>
<para>The <filename>virtusertable</filename> maps mail addresses for
virtual domains and
mailboxes to real mailboxes. These mailboxes can be local,
remote, aliases defined in
<filename>/etc/mail/aliases</filename> or files.</para>
<example>
<title>Example Virtual Domain Mail Map</title>
<programlisting>root@example.com root
postmaster@example.com postmaster@noc.example.net
@example.com joe</programlisting>
</example>
<para>In the above example, we have a mapping for a domain
<hostid role="domainname">example.com</hostid>. This file is processed in a
first match order down the file. The first item maps
<email>root@example.com</email> to the local mailbox <username>root</username>. The next entry maps
<email>postmaster@example.com</email> to the mailbox <username>postmaster</username> on the host
<hostid role="fqdn">noc.example.net</hostid>. Finally, if nothing from <hostid role="domainname">example.com</hostid> has
matched so far, it will match the last mapping, which matches
every other mail message addressed to someone at
<hostid role="domainname">example.com</hostid>.
This will be mapped to the local mailbox <username>joe</username>.</para>
</sect2>
</sect1>
<sect1 id="mail-changingmta">
<sect1info>
<authorgroup>
<author>
<firstname>Andrew</firstname>
<surname>Boothman</surname>
<contrib>Written by </contrib>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Gregory</firstname>
<surname>Neil Shapiro</surname>
<contrib>Information taken from e-mails written by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Changing Your Mail Transfer Agent</title>
<indexterm>
<primary>email</primary>
<secondary>change mta</secondary>
</indexterm>
<para>As already mentioned, FreeBSD comes with
<application>sendmail</application> already installed as your
MTA (Mail Transfer Agent). Therefore by default it is
in charge of your outgoing and incoming mail.</para>
<para>However, for a variety of reasons, some system
administrators want to change their system's MTA. These
reasons range from merely wanting to try out another MTA to
needing a specific feature or package which relies on another
mailer. Fortunately, whatever the reason, FreeBSD makes it
easy to make the change.</para>
<sect2>
<title>Install a New MTA</title>
<para>You have a wide choice of MTAs available. A good
starting point is the
<link linkend="ports">FreeBSD Ports Collection</link> where
you will be able to find many. Of course you are free to use
any MTA you want from any location, as long as you can make
it run under FreeBSD.</para>
<para>Start by installing your new MTA. Once it is installed
it gives you a chance to decide if it really fulfills your
needs, and also gives you the opportunity to configure your
new software before getting it to take over from
<application>sendmail</application>. When doing this, you
should be sure that installing the new software will not attempt
to overwrite system binaries such as
<filename>/usr/bin/sendmail</filename>. Otherwise, your new
mail software has essentially been put into service before
you have configured it.</para>
<para>Please refer to your chosen MTA's documentation for
information on how to configure the software you have
chosen.</para>
</sect2>
<sect2 id="mail-disable-sendmail">
<title>Disable <application>sendmail</application></title>
<warning>
<para>If you disable <application>sendmail</application>'s
outgoing mail service, it is important that you replace it
with an alternative mail delivery system. If
you choose not to, system functions such as &man.periodic.8;
will be unable to deliver their results by e-mail as they
would normally expect to. Many parts of your system may
expect to have a functional
<application>sendmail</application>-compatible system. If
applications continue to use
<application>sendmail</application>'s binaries to try to send
e-mail after you have disabled them, mail could go into an
inactive <application>sendmail</application> queue, and
never be delivered.</para>
</warning>
<para>In order to completely disable
<application>sendmail</application>, including the outgoing
mail service, you must use</para>
<programlisting>sendmail_enable="NO"
sendmail_submit_enable="NO"
sendmail_outbound_enable="NO"
sendmail_msp_queue_enable="NO"</programlisting>
<para>in <filename>/etc/rc.conf.</filename></para>
<para>If you only want to disable
<application>sendmail</application>'s incoming mail service,
you should set</para>
<programlisting>sendmail_enable="NO"</programlisting>
<para>in <filename>/etc/rc.conf</filename>. More information on
<application>sendmail</application>'s startup options is
available from the &man.rc.sendmail.8; manual page.</para>
</sect2>
<sect2>
<title>Running Your New MTA on Boot</title>
<para>The new MTA can be started during boot by adding a
configuration line to <filename>/etc/rc.conf</filename>
like the following example for postfix:</para>
<screen>&prompt.root; echo '<replaceable>postfix</replaceable>_enable=<quote>YES</quote>' >> /etc/rc.conf</screen>
<para>The MTA will now be automatically started during
boot.</para>
</sect2>
<sect2>
<title>Replacing <application>sendmail</application> as
the System's Default Mailer</title>
<para>The program <application>sendmail</application> is so ubiquitous
as standard software on &unix; systems that some software
just assumes it is already installed and configured.
For this reason, many alternative MTA's provide their own compatible
implementations of the <application>sendmail</application>
command-line interface; this facilitates using them as
<quote>drop-in</quote> replacements for <application>sendmail</application>.</para>
<para>Therefore, if you are using an alternative mailer,
you will need to make sure that software trying to execute
standard <application>sendmail</application> binaries such as
<filename>/usr/bin/sendmail</filename> actually executes
your chosen mailer instead. Fortunately, FreeBSD provides
a system called &man.mailwrapper.8; that does this job for
you.</para>
<para>When <application>sendmail</application> is operating as installed, you will
find something like the following
in <filename>/etc/mail/mailer.conf</filename>:</para>
<programlisting>sendmail /usr/libexec/sendmail/sendmail
send-mail /usr/libexec/sendmail/sendmail
mailq /usr/libexec/sendmail/sendmail
newaliases /usr/libexec/sendmail/sendmail
hoststat /usr/libexec/sendmail/sendmail
purgestat /usr/libexec/sendmail/sendmail</programlisting>
<para>This means that when any of these common commands
(such as <filename>sendmail</filename> itself) are run,
the system actually invokes a copy of mailwrapper named <filename>sendmail</filename>, which
checks <filename>mailer.conf</filename> and
executes <filename>/usr/libexec/sendmail/sendmail</filename>
instead. This system makes it easy to change what binaries
are actually executed when these default <filename>sendmail</filename> functions
are invoked.</para>
<para>Therefore if you wanted
<filename>/usr/local/supermailer/bin/sendmail-compat</filename>
to be run instead of <application>sendmail</application>, you could change
<filename>/etc/mail/mailer.conf</filename> to read:</para>
<programlisting>sendmail /usr/local/supermailer/bin/sendmail-compat
send-mail /usr/local/supermailer/bin/sendmail-compat
mailq /usr/local/supermailer/bin/mailq-compat
newaliases /usr/local/supermailer/bin/newaliases-compat
hoststat /usr/local/supermailer/bin/hoststat-compat
purgestat /usr/local/supermailer/bin/purgestat-compat</programlisting>
</sect2>
<sect2>
<title>Finishing</title>
<para>Once you have everything configured the way you want it, you should
either kill the <application>sendmail</application> processes that
you no longer need and start the processes belonging to your new
software, or simply reboot. Rebooting will also
give you the opportunity to ensure that you have correctly
configured your system to start your new MTA automatically on boot.</para>
</sect2>
</sect1>
<sect1 id="mail-trouble">
<title>Troubleshooting</title>
<indexterm>
<primary>email</primary>
<secondary>troubleshooting</secondary>
</indexterm>
<qandaset>
<qandaentry>
<question>
<para>Why do I have to use the FQDN for hosts on my site?</para>
</question>
<answer>
<para>You will probably find that the host is actually in a
different domain; for example, if you are in
<hostid role="fqdn">foo.bar.edu</hostid> and you wish to reach
a host called <hostid>mumble</hostid> in the <hostid
role="domainname">bar.edu</hostid> domain, you will have to
refer to it by the fully-qualified domain name, <hostid
role="fqdn">mumble.bar.edu</hostid>, instead of just
<hostid>mumble</hostid>.</para>
<indexterm><primary>BIND</primary></indexterm>
<para>Traditionally, this was allowed by BSD BIND resolvers.
However the current version of <application>BIND</application>
that ships with FreeBSD no longer provides default abbreviations
for non-fully qualified domain names other than the domain you
are in. So an unqualified host <hostid>mumble</hostid> must
either be found as <hostid
role="fqdn">mumble.foo.bar.edu</hostid>, or it will be searched
for in the root domain.</para>
<para>This is different from the previous behavior, where the
search continued across <hostid
role="domainname">mumble.bar.edu</hostid>, and <hostid
role="domainname">mumble.edu</hostid>. Have a look at RFC 1535
for why this was considered bad practice, or even a security
hole.</para>
<para>As a good workaround, you can place the line:</para>
<programlisting>search foo.bar.edu bar.edu</programlisting>
<para>instead of the previous:</para>
<programlisting>domain foo.bar.edu</programlisting>
<para>into your <filename>/etc/resolv.conf</filename>. However, make
sure that the search order does not go beyond the
<quote>boundary between local and public administration</quote>,
as RFC 1535 calls it.</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para><application>sendmail</application> says <errorname>mail
loops back to myself</errorname></para>
</question>
<answer>
<para>This is answered in the
<application>sendmail</application> FAQ as follows:</para>
<programlisting>I'm getting these error messages:
553 MX list for domain.net points back to relay.domain.net
554 <user@domain.net>... Local configuration error
How can I solve this problem?
You have asked mail to the domain (e.g., domain.net) to be
forwarded to a specific host (in this case, relay.domain.net)
by using an MX record, but the relay machine does not recognize
itself as domain.net. Add domain.net to /etc/mail/local-host-names
[known as /etc/sendmail.cw prior to version 8.10]
(if you are using FEATURE(use_cw_file)) or add <quote>Cw domain.net</quote>
to /etc/mail/sendmail.cf.</programlisting>
<para>The <application>sendmail</application> FAQ can be found at
<ulink url="http://www.sendmail.org/faq/"></ulink> and is
recommended reading if you want to do any
<quote>tweaking</quote> of your mail setup.</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>How can I run a mail server on a dial-up PPP host?</para>
</question>
<answer>
<para>You want to connect a FreeBSD box on a LAN to the
Internet. The FreeBSD box will be a mail gateway for the LAN.
The PPP connection is non-dedicated.</para>
<indexterm><primary>UUCP</primary></indexterm>
<indexterm>
<primary>MX record</primary>
</indexterm>
<para>There are at least two ways to do this. One way is to use
UUCP.</para>
<para>Another way is to get a full-time Internet server to provide secondary MX
services for your domain. For example, if your company's domain is
<hostid role="domainname">example.com</hostid> and your Internet service provider has
set <hostid role="domainname">example.net</hostid> up to provide secondary MX services
to your domain:</para>
<programlisting>example.com. MX 10 example.com.
MX 20 example.net.</programlisting>
<para>Only one host should be specified as the final recipient
(add <literal>Cw example.com</literal> in
<filename>/etc/mail/sendmail.cf</filename> on <hostid role="domainname">example.com</hostid>).</para>
<para>When the sending <command>sendmail</command> is trying to
deliver the mail it will try to connect to you (<hostid role="domainname">example.com</hostid>) over the modem
link. It will most likely time out because you are not online.
The program <application>sendmail</application> will automatically deliver it to the
secondary MX site, i.e., your Internet provider (<hostid role="domainname">example.net</hostid>). The secondary MX
site will then periodically try to connect to
your host and deliver the mail to the primary MX host (<hostid role="domainname">example.com</hostid>).</para>
<para>You might want to use something like this as a login
script:</para>
<programlisting>#!/bin/sh
# Put me in /usr/local/bin/pppmyisp
( sleep 60 ; /usr/sbin/sendmail -q ) &
/usr/sbin/ppp -direct pppmyisp</programlisting>
<para>If you are going to create a separate login script for a
user you could use <command>sendmail -qRexample.com</command>
instead in the script above. This will force all mail in your
queue for <hostid role="domainname">example.com</hostid> to be processed immediately.</para>
<para>A further refinement of the situation is as follows:</para>
<para>Message stolen from the &a.isp;.</para>
<programlisting>> we provide the secondary MX for a customer. The customer connects to
> our services several times a day automatically to get the mails to
> his primary MX (We do not call his site when a mail for his domains
> arrived). Our sendmail sends the mailqueue every 30 minutes. At the
> moment he has to stay 30 minutes online to be sure that all mail is
> gone to the primary MX.
>
> Is there a command that would initiate sendmail to send all the mails
> now? The user has not root-privileges on our machine of course.
In the <quote>privacy flags</quote> section of sendmail.cf, there is a
definition Opgoaway,restrictqrun
Remove restrictqrun to allow non-root users to start the queue processing.
You might also like to rearrange the MXs. We are the 1st MX for our
customers like this, and we have defined:
# If we are the best MX for a host, try directly instead of generating
# local config error.
OwTrue
That way a remote site will deliver straight to you, without trying
the customer connection. You then send to your customer. Only works for
<quote>hosts</quote>, so you need to get your customer to name their mail
machine <quote>customer.com</quote> as well as
<quote>hostname.customer.com</quote> in the DNS. Just put an A record in
the DNS for <quote>customer.com</quote>.</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>Why do I keep getting <errorname>Relaying
Denied</errorname> errors when sending mail from other
hosts?</para>
</question>
<answer>
<para>In default FreeBSD installations,
<application>sendmail</application> is configured to only
send mail from the host it is running on. For example, if
a <acronym>POP</acronym> server is available, then users
will be able to check mail from school, work, or other
remote locations but they still will not be able to send
outgoing emails from outside locations. Typically, a few
moments after the attempt, an email will be sent from
<application>MAILER-DAEMON</application> with a
<errorname>5.7 Relaying Denied</errorname> error
message.</para>
<para>There are several ways to get around this. The most
straightforward solution is to put your ISP's address in
a relay-domains file at
<filename>/etc/mail/relay-domains</filename>. A quick way
to do this would be:</para>
<screen>&prompt.root; <userinput>echo "your.isp.example.com" > /etc/mail/relay-domains</userinput></screen>
<para>After creating or editing this file you must restart
<application>sendmail</application>. This works great if
you are a server administrator and do not wish to send mail
locally, or would like to use a point and click
client/system on another machine or even another ISP. It
is also very useful if you only have one or two email
accounts set up. If there are a large number of addresses
to add, open this file in your favorite
text editor and then add the domains, one per line:</para>
<programlisting>your.isp.example.com
other.isp.example.net
users-isp.example.org
www.example.org</programlisting>
<para>Now any mail sent through your system, by any host in
this list (provided the user has an account on your
system), will succeed. This is a very nice way to allow
users to send mail from your system remotely without
allowing people to send SPAM through your system.</para>
</answer>
</qandaentry>
</qandaset>
</sect1>
<sect1 id="mail-advanced">
<title>Advanced Topics</title>
<para>The following section covers more involved topics such as mail
configuration and setting up mail for your entire domain.</para>
<sect2 id="mail-config">
<title>Basic Configuration</title>
<indexterm>
<primary>email</primary>
<secondary>configuration</secondary>
</indexterm>
<para>Out of the box, you should be able to send email to external
hosts as long as you have set up
<filename>/etc/resolv.conf</filename> or are running your own
name server. If you would like to have mail for your host
delivered to the MTA (e.g., <application>sendmail</application>) on your own FreeBSD host, there are two methods:</para>
<itemizedlist>
<listitem>
<para>Run your own name server and have your own domain. For
example, <hostid
role="domainname">FreeBSD.org</hostid></para>
</listitem>
<listitem>
<para>Get mail delivered directly to your host. This is done by
delivering mail directly to the current DNS name for your
machine. For example, <hostid
role="fqdn">example.FreeBSD.org</hostid>.</para>
</listitem>
</itemizedlist>
<indexterm><primary>SMTP</primary></indexterm>
<para>Regardless of which of the above you choose, in order to have
mail delivered directly to your host, it must have a permanent
static IP address (not a dynamic address, as with most PPP dial-up configurations). If you are behind a
firewall, it must pass SMTP traffic on to you. If you want to
receive mail directly at your host, you need to be sure of either of two
things:</para>
<itemizedlist>
<indexterm><primary>MX record</primary></indexterm>
<listitem>
<para>Make sure that the (lowest-numbered) MX record in your DNS points to your
host's IP address.</para>
</listitem>
<listitem>
<para>Make sure there is no MX entry in your DNS for your
host.</para>
</listitem>
</itemizedlist>
<para>Either of the above will allow you to receive mail directly at
your host.</para>
<para>Try this:</para>
<screen>&prompt.root; <userinput>hostname</userinput>
example.FreeBSD.org
&prompt.root; <userinput>host example.FreeBSD.org</userinput>
example.FreeBSD.org has address 204.216.27.XX</screen>
<para>If that is what you see, mail directly to
<email role="nolink">yourlogin@example.FreeBSD.org</email> should work without
problems (assuming <application>sendmail</application> is
running correctly on <hostid role="fqdn">example.FreeBSD.org</hostid>).</para>
<para>If instead you see something like this:</para>
<screen>&prompt.root; <userinput>host example.FreeBSD.org</userinput>
example.FreeBSD.org has address 204.216.27.XX
example.FreeBSD.org mail is handled (pri=10) by hub.FreeBSD.org</screen>
<para>All mail sent to your host (<hostid
role="fqdn">example.FreeBSD.org</hostid>) will end up being
collected on <hostid>hub</hostid> under the same username instead
of being sent directly to your host.</para>
<para>The above information is handled by your DNS server. The DNS
record that carries mail routing information is the
<emphasis>M</emphasis>ail e<emphasis>X</emphasis>change entry. If
no MX record exists, mail will be delivered directly to the host by
way of its IP address.</para>
<para>The MX entry for <hostid
role="fqdn">freefall.FreeBSD.org</hostid> at one time looked like
this:</para>
<programlisting>freefall MX 30 mail.crl.net
freefall MX 40 agora.rdrop.com
freefall MX 10 freefall.FreeBSD.org
freefall MX 20 who.cdrom.com</programlisting>
<para>As you can see, <hostid>freefall</hostid> had many MX entries.
The lowest MX number is the host that receives mail directly if
available; if it is not accessible for some reason, the others
(sometimes called <quote>backup MXes</quote>) accept messages
temporarily, and pass it along when a lower-numbered host becomes
available, eventually to the lowest-numbered host.</para>
<para>Alternate MX sites should have separate Internet connections
from your own in order to be most useful. Your ISP or another
friendly site should have no problem providing this service for
you.</para>
</sect2>
<sect2 id="mail-domain">
<title>Mail for Your Domain</title>
<para>In order to set up a <quote>mailhost</quote> (aka mail
server) you need to have any mail sent to various workstations
directed to it. Basically, you want to <quote>claim</quote> any
mail for any hostname in your domain (in this case <hostid
role="fqdn">*.FreeBSD.org</hostid>) and divert it to your mail
server so your users can receive their mail on
the master mail server.</para>
<indexterm><primary>DNS</primary></indexterm>
<para>To make life easiest, a user account with the same
<emphasis>username</emphasis> should exist on both machines. Use
&man.adduser.8; to do this.</para>
<para>The mailhost you will be using must be the designated mail
exchanger for each workstation on the network. This is done in
your DNS configuration like so:</para>
<programlisting>example.FreeBSD.org A 204.216.27.XX ; Workstation
MX 10 hub.FreeBSD.org ; Mailhost</programlisting>
<para>This will redirect mail for the workstation to the mailhost no
matter where the A record points. The mail is sent to the MX
host.</para>
<para>You cannot do this yourself unless you are running a DNS
server. If you are not, or cannot run your own DNS server, talk
to your ISP or whoever provides your DNS.</para>
<para>If you are doing virtual email hosting, the following
information will come in handy. For this example, we
will assume you have a customer with his own domain, in this
case <hostid role="domainname">customer1.org</hostid>, and you want
all the mail for <hostid role="domainname">customer1.org</hostid>
sent to your mailhost, <hostid
role="fqdn">mail.myhost.com</hostid>. The entry in your DNS
should look like this:</para>
<programlisting>customer1.org MX 10 mail.myhost.com</programlisting>
<para>You do <emphasis>not</emphasis> need an A record for <hostid role="domainname">customer1.org</hostid> if you only
want to handle email for that domain.</para>
<note>
<para>Be aware that pinging <hostid
role="domainname">customer1.org</hostid> will not work unless
an A record exists for it.</para>
</note>
<para>The last thing that you must do is tell
<application>sendmail</application> on your mailhost what domains
and/or hostnames it should be accepting mail for. There are a few
different ways this can be done. Either of the following will
work:</para>
<itemizedlist>
<listitem>
<para>Add the hosts to your
<filename>/etc/mail/local-host-names</filename> file if you are using the
<literal>FEATURE(use_cw_file)</literal>. If you are using
a version of <application>sendmail</application> earlier than 8.10, the file is
<filename>/etc/sendmail.cw</filename>.</para>
</listitem>
<listitem>
<para>Add a <literal>Cwyour.host.com</literal> line to your
<filename>/etc/sendmail.cf</filename> or
<filename>/etc/mail/sendmail.cf</filename> if you are using
<application>sendmail</application> 8.10 or higher.</para>
</listitem>
</itemizedlist>
</sect2>
</sect1>
<sect1 id="SMTP-UUCP">
<title>SMTP with UUCP</title>
<para>The <application>sendmail</application> configuration that ships with FreeBSD is
designed for sites that connect directly to the Internet. Sites
that wish to exchange their mail via UUCP must install another
<application>sendmail</application> configuration file.</para>
<para>Tweaking <filename>/etc/mail/sendmail.cf</filename> manually
is an advanced topic. <application>sendmail</application> version 8 generates config files
via &man.m4.1; preprocessing, where the actual configuration
occurs on a higher abstraction level. The &man.m4.1;
configuration files can be found under
<filename>/usr/share/sendmail/cf</filename>. The file
<filename>README</filename> in the <filename>cf</filename>
directory can serve as a basic introduction to &man.m4.1;
configuration.</para>
<para>The best way to support UUCP delivery is to use the
<literal>mailertable</literal> feature. This creates a database
that <application>sendmail</application> can use to make routing decisions.</para>
<para>First, you have to create your <filename>.mc</filename>
file. The directory
<filename>/usr/share/sendmail/cf/cf</filename> contains a
few examples. Assuming you have named your file
<filename>foo.mc</filename>, all you need to do in order to
convert it into a valid <filename>sendmail.cf</filename>
is:</para>
<screen>&prompt.root; <userinput>cd /etc/mail</userinput>
&prompt.root; <userinput>make foo.cf</userinput>
&prompt.root; <userinput>cp foo.cf /etc/mail/sendmail.cf</userinput></screen>
<para>A typical <filename>.mc</filename> file might look
like:</para>
<programlisting>VERSIONID(`<replaceable>Your version number</replaceable>') OSTYPE(bsd4.4)
FEATURE(accept_unresolvable_domains)
FEATURE(nocanonify)
FEATURE(mailertable, `hash -o /etc/mail/mailertable')
define(`UUCP_RELAY', <replaceable>your.uucp.relay</replaceable>)
define(`UUCP_MAX_SIZE', 200000)
define(`confDONT_PROBE_INTERFACES')
MAILER(local)
MAILER(smtp)
MAILER(uucp)
Cw <replaceable>your.alias.host.name</replaceable>
Cw <replaceable>youruucpnodename.UUCP</replaceable></programlisting>
<para>The lines containing
<literal>accept_unresolvable_domains</literal>,
<literal>nocanonify</literal>, and
<literal>confDONT_PROBE_INTERFACES</literal> features will
prevent any usage of the DNS during mail delivery. The
<literal>UUCP_RELAY</literal> clause is needed to support UUCP
delivery. Simply put an Internet hostname there that is able to
handle .UUCP pseudo-domain addresses; most likely, you will
enter the mail relay of your ISP there.</para>
<para>Once you have this, you need an
<filename>/etc/mail/mailertable</filename> file. If you have
only one link to the outside that is used for all your mails,
the following file will suffice:</para>
<programlisting>#
# makemap hash /etc/mail/mailertable.db < /etc/mail/mailertable
. uucp-dom:<replaceable>your.uucp.relay</replaceable></programlisting>
<para>A more complex example might look like this:</para>
<programlisting>#
# makemap hash /etc/mail/mailertable.db < /etc/mail/mailertable
#
horus.interface-business.de uucp-dom:horus
.interface-business.de uucp-dom:if-bus
interface-business.de uucp-dom:if-bus
.heep.sax.de smtp8:%1
horus.UUCP uucp-dom:horus
if-bus.UUCP uucp-dom:if-bus
. uucp-dom:</programlisting>
<para>The first three lines handle special cases where
domain-addressed mail should not be sent out to the default
route, but instead to some UUCP neighbor in order to
<quote>shortcut</quote> the delivery path. The next line handles
mail to the local Ethernet domain that can be delivered using
SMTP. Finally, the UUCP neighbors are mentioned in the .UUCP
pseudo-domain notation, to allow for a
<literal><replaceable>uucp-neighbor
</replaceable>!<replaceable>recipient</replaceable></literal>
override of the default rules. The last line is always a single
dot, matching everything else, with UUCP delivery to a UUCP
neighbor that serves as your universal mail gateway to the
world. All of the node names behind the
<literal>uucp-dom:</literal> keyword must be valid UUCP
neighbors, as you can verify using the command
<literal>uuname</literal>.</para>
<para>As a reminder that this file needs to be converted into a
DBM database file before use. The command line to accomplish
this is best placed as a comment at the top of the <filename>mailertable</filename> file.
You always have to execute this command each time you change
your <filename>mailertable</filename> file.</para>
<para>Final hint: if you are uncertain whether some particular
mail routing would work, remember the <option>-bt</option>
option to <application>sendmail</application>. It starts <application>sendmail</application> in <emphasis>address test
mode</emphasis>; enter <literal>3,0</literal>, followed
by the address you wish to test for the mail routing. The last
line tells you the used internal mail agent, the destination
host this agent will be called with, and the (possibly
translated) address. Leave this mode by typing <keycombo
action="simul"><keycap>Ctrl</keycap><keycap>D</keycap></keycombo>.</para>
<screen>&prompt.user; <userinput>sendmail -bt</userinput>
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
<prompt>></prompt> <userinput>3,0 foo@example.com</userinput>
canonify input: foo @ example . com
...
parse returns: $# uucp-dom $@ <replaceable>your.uucp.relay</replaceable> $: foo < @ example . com . >
<prompt>></prompt> <userinput>^D</userinput></screen>
</sect1>
<sect1 id="outgoing-only">
<sect1info>
<authorgroup>
<author>
<firstname>Bill</firstname>
<surname>Moran</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Setting Up to Send Only</title>
<para>There are many instances where you may only want to send
mail through a relay. Some examples are:</para>
<itemizedlist>
<listitem>
<para>Your computer is a desktop machine, but you want
to use programs such as &man.send-pr.1;. To do so, you should use
your ISP's mail relay.</para>
</listitem>
<listitem>
<para>The computer is a server that does not handle mail
locally, but needs to pass off all mail to a relay for
processing.</para>
</listitem>
</itemizedlist>
<para>Just about any <acronym>MTA</acronym> is capable of filling
this particular niche. Unfortunately, it can be very difficult
to properly configure a full-featured <acronym>MTA</acronym>
just to handle offloading mail. Programs such as
<application>sendmail</application> and
<application>postfix</application> are largely overkill for
this use.</para>
<para>Additionally, if you are using a typical Internet access
service, your agreement may forbid you from running a
<quote>mail server</quote>.</para>
<para>The easiest way to fulfill those needs is to install the
<filename role="package">mail/ssmtp</filename> port. Execute
the following commands as <username>root</username>:</para>
<screen>&prompt.root; <userinput>cd /usr/ports/mail/ssmtp</userinput>
&prompt.root; <userinput>make install replace clean</userinput></screen>
<para>Once installed,
<filename role="package">mail/ssmtp</filename> can be configured
with a four-line file located at
<filename>/usr/local/etc/ssmtp/ssmtp.conf</filename>:</para>
<programlisting>root=yourrealemail@example.com
mailhub=mail.example.com
rewriteDomain=example.com
hostname=_HOSTNAME_</programlisting>
<para>Make sure you use your real email address for
<username>root</username>. Enter your ISP's outgoing mail relay
in place of <hostid role="fqdn">mail.example.com</hostid> (some ISPs call
this the <quote>outgoing mail server</quote> or
<quote>SMTP server</quote>).</para>
<para>Make sure you disable <application>sendmail</application>,
including the outgoing mail service. See
<xref linkend="mail-disable-sendmail"/> for details.</para>
<para><filename role="package">mail/ssmtp</filename> has some
other options available. See the example configuration file in
<filename>/usr/local/etc/ssmtp</filename> or the manual page of
<application>ssmtp</application> for some examples and more
information.</para>
<para>Setting up <application>ssmtp</application> in this manner
will allow any software on your computer that needs to send
mail to function properly, while not violating your ISP's usage
policy or allowing your computer to be hijacked for spamming.</para>
</sect1>
<sect1 id="SMTP-dialup">
<title>Using Mail with a Dialup Connection</title>
<para>If you have a static IP address, you should not need to
adjust anything from the defaults. Set your host name to your
assigned Internet name and <application>sendmail</application> will do the rest.</para>
<para>If you have a dynamically assigned IP number and use a
dialup PPP connection to the Internet, you will probably have a
mailbox on your ISPs mail server. Let's assume your ISP's domain
is <hostid role="domainname">example.net</hostid>, and that your
user name is <username>user</username>, you have called your
machine <hostid role="fqdn">bsd.home</hostid>, and your ISP has
told you that you may use <hostid
role="fqdn">relay.example.net</hostid> as a mail relay.</para>
<para>In order to retrieve mail from your mailbox, you must
install a retrieval agent. The
<application>fetchmail</application> utility is a good choice as
it supports many different protocols. This program is available
as a package or from the Ports Collection (<filename
role="package">mail/fetchmail</filename>). Usually, your <acronym>ISP</acronym> will
provide <acronym>POP</acronym>. If you are using user <acronym>PPP</acronym>, you can
automatically fetch your mail when an Internet connection is
established with the following entry in
<filename>/etc/ppp/ppp.linkup</filename>:</para>
<programlisting>MYADDR:
!bg su user -c fetchmail</programlisting>
<para>If you are using <application>sendmail</application> (as
shown below) to deliver mail to non-local accounts, you probably
want to have <application>sendmail</application> process your
mailqueue as soon as your Internet connection is established.
To do this, put this command after the
<command>fetchmail</command> command in
<filename>/etc/ppp/ppp.linkup</filename>:</para>
<programlisting> !bg su user -c "sendmail -q"</programlisting>
<para>Assume that you have an account for
<username>user</username> on <hostid
role="fqdn">bsd.home</hostid>. In the home directory of
<username>user</username> on <hostid
role="fqdn">bsd.home</hostid>, create a
<filename>.fetchmailrc</filename> file:</para>
<programlisting>poll example.net protocol pop3 fetchall pass MySecret</programlisting>
<para>This file should not be readable by anyone except
<username>user</username> as it contains the password
<literal>MySecret</literal>.</para>
<para>In order to send mail with the correct
<literal>from:</literal> header, you must tell
<application>sendmail</application> to use
<email>user@example.net</email> rather than
<email role="nolink">user@bsd.home</email>. You may also wish to tell
<application>sendmail</application> to send all mail via <hostid
role="fqdn">relay.example.net</hostid>, allowing quicker mail
transmission.</para>
<para>The following <filename>.mc</filename> file should
suffice:</para>
<programlisting>VERSIONID(`bsd.home.mc version 1.0')
OSTYPE(bsd4.4)dnl
FEATURE(nouucp)dnl
MAILER(local)dnl
MAILER(smtp)dnl
Cwlocalhost
Cwbsd.home
MASQUERADE_AS(`example.net')dnl
FEATURE(allmasquerade)dnl
FEATURE(masquerade_envelope)dnl
FEATURE(nocanonify)dnl
FEATURE(nodns)dnl
define(`SMART_HOST', `relay.example.net')
Dmbsd.home
define(`confDOMAIN_NAME',`bsd.home')dnl
define(`confDELIVERY_MODE',`deferred')dnl</programlisting>
<para>Refer to the previous section for details of how to turn
this <filename>.mc</filename> file into a
<filename>sendmail.cf</filename> file. Also, do not forget to
restart <application>sendmail</application> after updating
<filename>sendmail.cf</filename>.</para>
</sect1>
<sect1 id="SMTP-Auth">
<sect1info>
<authorgroup>
<author>
<firstname>James</firstname>
<surname>Gorham</surname>
<contrib>Written by </contrib>
</author>
</authorgroup>
</sect1info>
<title>SMTP Authentication</title>
<para>Having <acronym>SMTP</acronym> Authentication in place on
your mail server has a number of benefits.
<acronym>SMTP</acronym> Authentication can add another layer
of security to <application>sendmail</application>, and has the benefit of giving mobile
users who switch hosts the ability to use the same mail server
without the need to reconfigure their mail client settings
each time.</para>
<procedure>
<step>
<para>Install <filename role="package">security/cyrus-sasl2</filename>
from the ports. You can find this port in
<filename role="package">security/cyrus-sasl2</filename>. The
<filename role="package">security/cyrus-sasl2</filename> port
supports a number of compile-time options. For the SMTP
Authentication method we will be using here, make sure that
the <option>LOGIN</option> option is not disabled.</para>
</step>
<step>
<para>After installing <filename role="package">security/cyrus-sasl2</filename>,
edit <filename>/usr/local/lib/sasl2/Sendmail.conf</filename>
(or create it if it does not exist) and add the following
line:</para>
<programlisting>pwcheck_method: saslauthd</programlisting>
</step>
<step>
<para>Next, install <filename role="package">security/cyrus-sasl2-saslauthd</filename>,
edit <filename>/etc/rc.conf</filename> to add the following
line:</para>
<programlisting>saslauthd_enable="YES"</programlisting>
<para>and finally start the saslauthd daemon:</para>
<screen>&prompt.root; <userinput>service saslauthd start</userinput></screen>
<para>This daemon serves as a broker for <application>sendmail</application> to
authenticate against your FreeBSD <filename>passwd</filename>
database. This saves the trouble of creating a new set of usernames
and passwords for each user that needs to use
<acronym>SMTP</acronym> authentication, and keeps the login
and mail password the same.</para>
</step>
<step>
<para>Now edit <filename>/etc/make.conf</filename> and add the
following lines:</para>
<programlisting>SENDMAIL_CFLAGS=-I/usr/local/include/sasl -DSASL
SENDMAIL_LDFLAGS=-L/usr/local/lib
SENDMAIL_LDADD=-lsasl2</programlisting>
<para>These lines will give <application>sendmail</application>
the proper configuration options for linking
to <filename role="package">cyrus-sasl2</filename> at compile time.
Make sure that <filename role="package">cyrus-sasl2</filename>
has been installed before recompiling
<application>sendmail</application>.</para>
</step>
<step>
<para>Recompile <application>sendmail</application> by executing the following commands:</para>
<screen>&prompt.root; <userinput>cd /usr/src/lib/libsmutil</userinput>
&prompt.root; <userinput>make cleandir && make obj && make</userinput>
&prompt.root; <userinput>cd /usr/src/lib/libsm</userinput>
&prompt.root; <userinput>make cleandir && make obj && make</userinput>
&prompt.root; <userinput>cd /usr/src/usr.sbin/sendmail</userinput>
&prompt.root; <userinput>make cleandir && make obj && make && make install</userinput></screen>
<para>The compile of <application>sendmail</application> should not have any problems
if <filename>/usr/src</filename> has not been changed extensively
and the shared libraries it needs are available.</para>
</step>
<step>
<para>After <application>sendmail</application> has been compiled
and reinstalled, edit your <filename>/etc/mail/freebsd.mc</filename>
file (or whichever file you use as your <filename>.mc</filename> file. Many administrators
choose to use the output from &man.hostname.1; as the <filename>.mc</filename> file for
uniqueness). Add these lines to it:</para>
<programlisting>dnl set SASL options
TRUST_AUTH_MECH(`GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl
define(`confAUTH_MECHANISMS', `GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl</programlisting>
<para>These options configure the different methods available to
<application>sendmail</application> for authenticating users.
If you would like to use a method other than
<application>pwcheck</application>, please see the
included documentation.</para>
</step>
<step>
<para>Finally, run &man.make.1; while in <filename>/etc/mail</filename>.
That will run your new <filename>.mc</filename> file and create a <filename>.cf</filename> file named
<filename>freebsd.cf</filename> (or whatever name you have used
for your <filename>.mc</filename> file). Then use the
command <command>make install restart</command>, which will
copy the file to <filename>sendmail.cf</filename>, and will
properly restart <application>sendmail</application>.
For more information about this process, you should refer
to <filename>/etc/mail/Makefile</filename>.</para>
</step>
</procedure>
<para>If all has gone correctly, you should be able to enter your login
information into the mail client and send a test message.
For further investigation, set the <option>LogLevel</option> of
<application>sendmail</application> to 13 and watch
<filename>/var/log/maillog</filename> for any errors.</para>
<para>For more information, please see the <application>sendmail</application>
page regarding
<ulink url="http://www.sendmail.org/~ca/email/auth.html">
<acronym>SMTP</acronym> authentication</ulink>.</para>
</sect1>
<sect1 id="mail-agents">
<sect1info>
<authorgroup>
<author>
<firstname>Marc</firstname>
<surname>Silver</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Mail User Agents</title>
<indexterm>
<primary>Mail User Agents</primary>
</indexterm>
<para>A Mail User Agent (<acronym>MUA</acronym>) is an application
that is used to send and receive email. Furthermore, as email
<quote>evolves</quote> and becomes more complex,
<acronym>MUA</acronym>'s are becoming increasingly powerful in the
way they interact with email; this gives users increased
functionality and flexibility. &os; contains support for
numerous mail user agents, all of which can be easily installed
using the <link linkend="ports">FreeBSD Ports Collection</link>.
Users may choose between graphical email clients such as
<application>evolution</application> or
<application>balsa</application>, console based clients such as
<application>mutt</application>, <application>alpine</application>
or <command>mail</command>, or the web interfaces used by some
large organizations.</para>
<sect2 id="mail-command">
<title>mail</title>
<para>&man.mail.1; is the default Mail User Agent
(<acronym>MUA</acronym>) in &os;. It is a
console based <acronym>MUA</acronym> that offers all the basic
functionality required to send and receive text-based email,
though it is limited in interaction abilities with attachments
and can only support local mailboxes.</para>
<para>Although <command>mail</command> does not natively support
interaction with <acronym>POP</acronym> or
<acronym>IMAP</acronym> servers, these mailboxes may be
downloaded to a local <filename>mbox</filename> file using an
application such as <application>fetchmail</application>, which
will be discussed later in this chapter (<xref
linkend="mail-fetchmail"/>).</para>
<para>In order to send and receive email, run
<command>mail</command>:</para>
<screen>&prompt.user; <userinput>mail</userinput></screen>
<para>The contents of the user mailbox in
<filename class="directory">/var/mail</filename> are
automatically read by the <command>mail</command> utility.
Should the mailbox be empty, the utility exits with a
message indicating that no mails could be found. Once the
mailbox has been read, the application interface is started, and
a list of messages will be displayed. Messages are automatically
numbered, as can be seen in the following example:</para>
<screen>Mail version 8.1 6/6/93. Type ? for help.
"/var/mail/marcs": 3 messages 3 new
>N 1 root@localhost Mon Mar 8 14:05 14/510 "test"
N 2 root@localhost Mon Mar 8 14:05 14/509 "user account"
N 3 root@localhost Mon Mar 8 14:05 14/509 "sample"</screen>
<para>Messages can now be read by using the <keycap>t</keycap>
<command>mail</command> command, suffixed by the message number
that should be displayed. In this example, we will read the
first email:</para>
<screen>& <userinput>t 1</userinput>
Message 1:
From root@localhost Mon Mar 8 14:05:52 2004
X-Original-To: marcs@localhost
Delivered-To: marcs@localhost
To: marcs@localhost
Subject: test
Date: Mon, 8 Mar 2004 14:05:52 +0200 (SAST)
From: root@localhost (Charlie Root)
This is a test message, please reply if you receive it.</screen>
<para>As can be seen in the example above, the <keycap>t</keycap>
key will cause the message to be displayed with full headers.
To display the list of messages again, the <keycap>h</keycap>
key should be used.</para>
<para>If the email requires a response, you may use
<command>mail</command> to reply, by using either the
<keycap>R</keycap> or <keycap>r</keycap> <command>mail</command>
keys. The <keycap>R</keycap> key instructs
<command>mail</command> to reply only to the sender of the
email, while <keycap>r</keycap> replies not only to the sender,
but also to other recipients of the message. You may also
suffix these commands with the mail number which you would like
make a reply to. Once this has been done, the response should
be entered, and the end of the message should be marked by a
single <keycap>.</keycap> on a new line. An example can be seen
below:</para>
<screen>& <userinput>R 1</userinput>
To: root@localhost
Subject: Re: test
<userinput>Thank you, I did get your email.
.</userinput>
EOT</screen>
<para>In order to send new email, the <keycap>m</keycap>
key should be used, followed by the
recipient email address. Multiple recipients may also be
specified by separating each address with the <keycap>,</keycap>
delimiter. The subject of the message may then be entered,
followed by the message contents. The end of the message should
be specified by putting a single <keycap>.</keycap> on a new
line.</para>
<screen>& <userinput>mail root@localhost</userinput>
Subject: <userinput>I mastered mail
Now I can send and receive email using mail ... :)
.</userinput>
EOT</screen>
<para>While inside the <command>mail</command> utility, the
<keycap>?</keycap> command may be used to display help at any
time, the &man.mail.1; manual page should also be consulted for
more help with <command>mail</command>.</para>
<note>
<para>As previously mentioned, the &man.mail.1; command was not
originally designed to handle attachments, and thus deals with
them very poorly. Newer <acronym>MUA</acronym>s such as
<application>mutt</application> handle attachments in a much
more intelligent way. But should you still wish to use the
<command>mail</command> command, the <filename
role="package">converters/mpack</filename> port may be of
considerable use.</para>
</note>
</sect2>
<sect2 id="mutt-command">
<title>mutt</title>
<para><application>mutt</application> is a small yet very
powerful Mail User Agent, with excellent features,
just some of which include:</para>
<itemizedlist>
<listitem>
<para>The ability to thread messages;</para>
</listitem>
<listitem>
<para>PGP support for digital signing and encryption of
email;</para>
</listitem>
<listitem>
<para>MIME Support;</para>
</listitem>
<listitem>
<para>Maildir Support;</para>
</listitem>
<listitem>
<para>Highly customizable.</para>
</listitem>
</itemizedlist>
<para>All of these features help to make
<application>mutt</application> one of the most advanced mail
user agents available. See <ulink
url="http://www.mutt.org"></ulink> for more
information on <application>mutt</application>.</para>
<para>The stable version of <application>mutt</application> may be
installed using the <filename
role="package">mail/mutt</filename> port, while the current
development version may be installed via the <filename
role="package">mail/mutt-devel</filename> port. After the port
has been installed, <application>mutt</application> can be
started by issuing the following command:</para>
<screen>&prompt.user; <userinput>mutt</userinput></screen>
<para><application>mutt</application> will automatically read the
contents of the user mailbox in <filename
class="directory">/var/mail</filename> and display the contents
if applicable. If no mails are found in the user mailbox, then
<application>mutt</application> will wait for commands from the
user. The example below shows <application>mutt</application>
displaying a list of messages:</para>
<mediaobject>
<imageobject>
<imagedata fileref="mail/mutt1" format="PNG"/>
</imageobject>
</mediaobject>
<para>In order to read an email, select it using the cursor
keys and press the <keycap>Enter</keycap> key. An example of
<application>mutt</application> displaying email can be seen
below:</para>
<mediaobject>
<imageobject>
<imagedata fileref="mail/mutt2" format="PNG"/>
</imageobject>
</mediaobject>
<para>As with the &man.mail.1; command,
<application>mutt</application> allows users to reply only to
the sender of the message as well as to all recipients. To
reply only to the sender of the email, use the
<keycap>r</keycap> keyboard shortcut. To send a group reply,
which will be sent to the original sender as well as all the
message recipients, use the <keycap>g</keycap> shortcut.</para>
<note>
<para><application>mutt</application> makes use of the
&man.vi.1; command as an editor for creating and replying to
emails. This may be customized by the user by creating or
editing their own <filename>.muttrc</filename> file in their home directory and setting the
<literal>editor</literal> variable or by setting the
<envar>EDITOR</envar> environment variable. See
<ulink url="http://www.mutt.org/"></ulink> for more
information about configuring
<application>mutt</application>.</para>
</note>
<para>In order to compose a new mail message, press
<keycap>m</keycap>. After a valid subject has been given,
<application>mutt</application> will start &man.vi.1; and the
mail can be written. Once the contents of the mail are
complete, save and quit from <command>vi</command> and
<application>mutt</application> will resume, displaying a
summary screen of the mail that is to be delivered. In order to
send the mail, press <keycap>y</keycap>. An example of the
summary screen can be seen below:</para>
<mediaobject>
<imageobject>
<imagedata fileref="mail/mutt3" format="PNG"/>
</imageobject>
</mediaobject>
<para><application>mutt</application> also contains extensive
help, which can be accessed from most of the menus by pressing
the <keycap>?</keycap> key. The top line also displays the
keyboard shortcuts where appropriate.</para>
</sect2>
<sect2 id="alpine-command">
<title>alpine</title>
<para><application>alpine</application> is aimed at a beginner
user, but also includes some advanced features.</para>
<warning>
<para>The <application>alpine</application> software has had several remote vulnerabilities
discovered in the past, which allowed remote attackers to
execute arbitrary code as users on the local system, by the
action of sending a specially-prepared email. All such
<emphasis>known</emphasis> problems have been fixed, but the
<application>alpine</application> code is written in a very insecure style and the &os;
Security Officer believes there are likely to be other
undiscovered vulnerabilities. You install
<application>alpine</application> at your own risk.</para>
</warning>
<para>The current version of <application>alpine</application> may
be installed using the <filename
role="package">mail/alpine</filename> port. Once the port has
installed, <application>alpine</application> can be started by
issuing the following command:</para>
<screen>&prompt.user; <userinput>alpine</userinput></screen>
<para>The first time that <application>alpine</application> is run
it displays a greeting page with a brief introduction, as well
as a request from the <application>alpine</application>
development team to send an anonymous email message allowing
them to judge how many users are using their client. To send
this anonymous message, press <keycap>Enter</keycap>, or
alternatively press <keycap>E</keycap> to exit the greeting
without sending an anonymous message. An example of the
greeting page can be seen below:</para>
<mediaobject>
<imageobject>
<imagedata fileref="mail/pine1" format="PNG"/>
</imageobject>
</mediaobject>
<para>Users are then presented with the main menu, which can be
easily navigated using the cursor keys. This main menu provides
shortcuts for the composing new mails, browsing of mail directories,
and even the administration of address book entries. Below the
main menu, relevant keyboard shortcuts to perform functions
specific to the task at hand are shown.</para>
<para>The default directory opened by <application>alpine</application>
is the <filename class="directory">inbox</filename>. To view the message index, press
<keycap>I</keycap>, or select the <guimenuitem>MESSAGE INDEX</guimenuitem>
option as seen below:</para>
<mediaobject>
<imageobject>
<imagedata fileref="mail/pine2" format="PNG"/>
</imageobject>
</mediaobject>
<para>The message index shows messages in the current directory,
and can be navigated by using the cursor keys. Highlighted
messages can be read by pressing the
<keycap>Enter</keycap> key.</para>
<mediaobject>
<imageobject>
<imagedata fileref="mail/pine3" format="PNG"/>
</imageobject>
</mediaobject>
<para>In the screenshot below, a sample message is displayed by
<application>alpine</application>. Keyboard shortcuts are
displayed as a reference at the bottom of the screen. An
example of one of these shortcuts is the <keycap>r</keycap> key,
which tells the <acronym>MUA</acronym> to reply to the current
message being displayed.</para>
<mediaobject>
<imageobject>
<imagedata fileref="mail/pine4" format="PNG"/>
</imageobject>
</mediaobject>
<para>Replying to an email in <application>alpine</application> is
done using the <application>pico</application> editor, which is
installed by default with <application>alpine</application>.
The <application>pico</application> utility makes it easy to
navigate around the message and is slightly more forgiving on
novice users than &man.vi.1; or &man.mail.1;. Once the reply
is complete, the message can be sent by pressing
<keycombo action="simul"><keycap>Ctrl</keycap><keycap>X</keycap>
</keycombo>. The <application>alpine</application> application
will ask for confirmation.</para>
<mediaobject>
<imageobject>
<imagedata fileref="mail/pine5" format="PNG"/>
</imageobject>
</mediaobject>
<para>The <application>alpine</application> application can be
customized using the <guimenuitem>SETUP</guimenuitem> option from the main
menu. Consult <ulink url="http://www.washington.edu/alpine/"></ulink>
for more information.</para>
</sect2>
</sect1>
<sect1 id="mail-fetchmail">
<sect1info>
<authorgroup>
<author>
<firstname>Marc</firstname>
<surname>Silver</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Using fetchmail</title>
<indexterm>
<primary>fetchmail</primary>
</indexterm>
<para><application>fetchmail</application> is a full-featured
<acronym>IMAP</acronym> and <acronym>POP</acronym> client which
allows users to automatically download mail from remote
<acronym>IMAP</acronym> and <acronym>POP</acronym> servers and
save it into local mailboxes; there it can be accessed more easily.
<application>fetchmail</application> can be installed using the
<filename role="package">mail/fetchmail</filename> port, and
offers various features, some of which include:</para>
<itemizedlist>
<listitem>
<para>Support of <acronym>POP3</acronym>,
<acronym>APOP</acronym>, <acronym>KPOP</acronym>,
<acronym>IMAP</acronym>, <acronym>ETRN</acronym> and
<acronym>ODMR</acronym> protocols.</para>
</listitem>
<listitem>
<para>Ability to forward mail using <acronym>SMTP</acronym>, which
allows filtering, forwarding, and aliasing to function
normally.</para>
</listitem>
<listitem>
<para>May be run in daemon mode to check periodically for new
messages.</para>
</listitem>
<listitem>
<para>Can retrieve multiple mailboxes and forward them based
on configuration, to different local users.</para>
</listitem>
</itemizedlist>
<para>While it is outside the scope of this document to explain
all of <application>fetchmail</application>'s features, some
basic features will be explained. The
<application>fetchmail</application> utility requires a
configuration file known as <filename>.fetchmailrc</filename>,
in order to run correctly. This file includes server information
as well as login credentials. Due to the sensitive nature of the
contents of this file, it is advisable to make it readable only by the owner,
with the following command:</para>
<screen>&prompt.user; <userinput>chmod 600 .fetchmailrc</userinput></screen>
<para>The following <filename>.fetchmailrc</filename> serves as an
example for downloading a single user mailbox using
<acronym>POP</acronym>. It tells
<application>fetchmail</application> to connect to <hostid
role="fqdn">example.com</hostid> using a username of
<username>joesoap</username> and a password of
<literal>XXX</literal>. This example assumes that the user
<username>joesoap</username> is also a user on the local
system.</para>
<programlisting>poll example.com protocol pop3 username "joesoap" password "XXX"</programlisting>
<para>The next example connects to multiple <acronym>POP</acronym>
and <acronym>IMAP</acronym> servers and redirects to different
local usernames where applicable:</para>
<programlisting>poll example.com proto pop3:
user "joesoap", with password "XXX", is "jsoap" here;
user "andrea", with password "XXXX";
poll example2.net proto imap:
user "john", with password "XXXXX", is "myth" here;</programlisting>
<para>The <application>fetchmail</application> utility can be run in daemon
mode by running it with the <option>-d</option> flag, followed
by the interval (in seconds) that
<application>fetchmail</application> should poll servers listed
in the <filename>.fetchmailrc</filename> file. The following
example would cause <application>fetchmail</application> to poll
every 600 seconds:</para>
<screen>&prompt.user; <userinput>fetchmail -d 600</userinput></screen>
<para>More information on <application>fetchmail</application> can
be found at <ulink
url="http://fetchmail.berlios.de/"></ulink>.</para>
</sect1>
<sect1 id="mail-procmail">
<sect1info>
<authorgroup>
<author>
<firstname>Marc</firstname>
<surname>Silver</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Using procmail</title>
<indexterm>
<primary>procmail</primary>
</indexterm>
<para>The <application>procmail</application> utility is an
incredibly powerful application used to filter incoming mail.
It allows users to define <quote>rules</quote> which can be
matched to incoming mails to perform specific functions or to
reroute mail to alternative mailboxes and/or email addresses.
<application>procmail</application> can be installed using the
<filename role="package">mail/procmail</filename> port. Once
installed, it can be directly integrated into most
<acronym>MTA</acronym>s; consult your <acronym>MTA</acronym>
documentation for more information. Alternatively,
<application>procmail</application> can be integrated by adding
the following line to a <filename>.forward</filename> in the home
directory of the user utilizing
<application>procmail</application> features:</para>
<programlisting>"|exec /usr/local/bin/procmail || exit 75"</programlisting>
<para>The following section will display some basic
<application>procmail</application> rules, as well as brief
descriptions on what they do. These rules, and others must be
inserted into a <filename>.procmailrc</filename> file, which
must reside in the user's home directory.</para>
<para>The majority of these rules can also be found in the
&man.procmailex.5; manual page.</para>
<para>Forward all mail from <email>user@example.com</email> to an
external address of <email role="nolink">goodmail@example2.com</email>:</para>
<programlisting>:0
* ^From.*user@example.com
! goodmail@example2.com</programlisting>
<para>Forward all mails shorter than 1000 bytes to an external
address of <email role="nolink">goodmail@example2.com</email>:</para>
<programlisting>:0
* < 1000
! goodmail@example2.com</programlisting>
<para>Send all mail sent to <email>alternate@example.com</email>
into a mailbox called <filename>alternate</filename>:</para>
<programlisting>:0
* ^TOalternate@example.com
alternate</programlisting>
<para>Send all mail with a subject of <quote>Spam</quote> to
<filename>/dev/null</filename>:</para>
<programlisting>:0
^Subject:.*Spam
/dev/null</programlisting>
<para>A useful recipe that parses incoming <hostid role="domainname">&os;.org</hostid> mailing lists
and places each list in its own mailbox:</para>
<programlisting>:0
* ^Sender:.owner-freebsd-\/[^@]+@FreeBSD.ORG
{
LISTNAME=${MATCH}
:0
* LISTNAME??^\/[^@]+
FreeBSD-${MATCH}
}</programlisting>
</sect1>
</chapter>