<listitem><para>How to replace <application>sendmail</application>

      as your system's default mailer.</para>

      </listitem>

  <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 MTA</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 simply 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 new MTA</title>

      <para>You have a wide choice of MTAs available to you.  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 insure that installing the new software won't 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>

      <title>Disable <application>sendmail</application></title>

      <para>The procedure used to start 

       <application>sendmail</application> changed significantly 

       between 4.5-RELEASE and 4.6-RELEASE.  Therefore, the procedure 

       used to disable it is subtly different.</para>

      <sect3>

        <title>FreeBSD 4.5-STABLE before 2002/4/4 and earlier 

         (including 4.5-RELEASE and earlier)</title>

        <para>Enter 

         <programlisting>sendmail_enable="NO"</programlisting> into

         <filename>/etc/rc.conf</filename>.  This will disable 

         <application>sendmail</application>'s incoming mail service, 

         but if <filename>/etc/mail/mailer.conf</filename> (see below)

         is not changed, <application>sendmail</application> will 

         still be used to send e-mail.</para>

      </sect3>

      <sect3>

        <title>FreeBSD 4.5-STABLE after 2002/4/4 

         (including 4.6-RELEASE and later)</title>

        <para>In order to completely disable 

         <application>sendmail</application> you must use 

         <programlisting>sendmail_enable="NONE"</programlisting> in 

         <filename>/etc/rc.conf</filename></para>

        <warning>

          <para>If you disable <application>sendmail</application>'s 

           outgoing mail service in this way, it is important that you 

           replace it with a fully working 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 and send 

           e-mail after you have disabled it, the mail may transparently 

           queue forever.</para>

        </warning>

        <para>If you only want to disable 

         <application>sendmail</application>'s incoming mail service, 

         you should set 

         <programlisting>sendmail_enable="NO"</programlisting> 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>

      </sect3>

    <sect2>

      <title>Running your new MTA on boot</title>

      <para>You may have a choice of two methods for running your 

       new MTA on boot, again depending on what version of FreeBSD 

       you are running.</para>

      <sect3>

        <title>FreeBSD 4.5-STABLE before 2002/4/11 

         (including 4.5-RELEASE and earlier)</title>

        <para>Add a script into 

         <filename>/usr/local/etc/rc.d/</filename> that

         ends in <filename>.sh</filename> and is executable by 

         root.  The script should also accept the parameters 'start' 

         or 'stop'.  So that you could, for example, execute 

         <filename>/usr/local/etc/rc.d/supermailer.sh start</filename>

         or <filename>/usr/local/etc/rc.d/supermailer.sh stop</filename>.  

         The system will call your script using 'start' when the it 

         boots and using 'stop' when the it shuts down.</para>

      </sect3>

      <sect3>

        <title>FreeBSD 4.5-STABLE after 2002/4/11 

         (including 4.6-RELEASE and later)</title>

        <para>With later versions of FreeBSD, you can use the 

         above method or you can also set 

         <programlisting>mta_start_script="<replaceable>filename</replaceable>"</programlisting>

         in <filename>/etc/rc.conf</filename>, where 

         <replaceable>filename</replaceable> is the name of some 

         script that you want executed on boot to start your 

         MTA.</para>

      </sect3>

    </sect2>

    <sect2>

      <title>Replacing <application>sendmail</application> as 

       the system's default mailer</title>

      <para><application>Sendmail</application> is so ubiquitous 

       as standard software on Unix systems, that some software 

       just presumes that it is already installed and configured.  

       For this reason, many alternative MTA's provide utilities 

       that implement exactly the same command-line interface 

       that <application>sendmail</application> provides.</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> : <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>

      <para>This means that when any of these common command 

       are run, such as <filename>/usr/bin/sendmail</filename> 

       the program that is actually sitting in that location 

       checks <filename>mailer.conf</filename> and actually 

       executes <filename>/usr/libexec/sendmail/sendmail</filename> 

       instead.  This system makes it easy to change what binaries 

       are actually executed when these default system utilites 

       are run.</para>

      <para>Therefore if you wanted 

       <filename>/usr/local/supermailer/bin/sendmail-compat</filename>

       to be run instead of sendmail, you would change

       <filename>/etc/mail/mailer.conf</filename> to read : <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>

       </para>

     </sect2>

     <sect2>

       <title>Finishing</title>

       <para>Once you have everything configured how 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 you should reboot your machine.  Rebooting will also 

        give you the opportunity to ensure that you have correctly 

        configured your machine to start your new MTA on boot.</para>

     </sect2> 

  </sect1>