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Various improvements to the mail chapter:

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- Use <hostid> for domain names.
- Wrap sendmail in <application> where appropriate.
- Expand on /usr/local/etc/rc.d script start/stop functionality.
- Explain how mailer.conf works in a bit more detail.
- Add to the description of MX records and backup MX servers.
- Reword and improve various parts, fixing grammar and typos.

PR:		docs/38318
Submitted by:	Chris Pepper <pepper@reppep.com>
This commit is contained in:
Giorgos Keramidas 2002-05-22 04:07:41 +00:00
parent 002e04c79e
commit 2e86ad20cd
Notes: svn2git 2020-12-08 03:00:23 +00:00 
svn path=/head/; revision=13186
1 changed files with 79 additions and 67 deletions
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en_US.ISO8859-1/books/handbook/mail/chapter.sgml
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@ -397,7 +397,7 @@ procmail: "|/usr/local/bin/procmail"</programlisting>
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 example.com and the host
domain <hostid role="domainname">example.com</hostid> and the host
<hostid>mail.example.com</hostid>, its
<filename>local-host-names</filename> might look something like
this:</para>
@ -406,7 +406,7 @@ procmail: "|/usr/local/bin/procmail"</programlisting>
mail.example.com</programlisting>
<para>When this file is updated, &man.sendmail.8; needs to be
restarted for it to read the changes.</para>
restarted to read the changes.</para>
</sect2>
@ -416,15 +416,15 @@ mail.example.com</programlisting>
<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 reject messages for
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 features
and behavior of sendmail. Please see
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>
@ -436,11 +436,11 @@ mail.example.com</programlisting>
<sect2>
<title><filename>/etc/mail/virtusertable</filename></title>
<para>The <filename>virtualusertable</filename> maps mail for
<para>The <filename>virtusertable</filename> maps mail addresses for
virtual domains and
mailboxes to real mailboxes. These mailboxes can be local,
remote, an alias defined in
<filename>/etc/mail/aliases</filename> or a file.</para>
remote, aliases defined in
<filename>/etc/mail/aliases</filename> or files.</para>
<example>
<title>Example Virtual Domain Mail Map</title>
@ -570,8 +570,8 @@ postmaster@example.com postmaster@noc.example.net
<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>
e-mail after you have disabled them, mail could go into an
inactive <application>sendmail</application> queue, and never be delivered.</para>
</warning>
<para>If you only want to disable
@ -599,12 +599,20 @@ postmaster@example.com postmaster@noc.example.net
<para>Add a script to
<filename>/usr/local/etc/rc.d/</filename> that
ends in <filename>.sh</filename> and is executable by
<username>root</username>. The script should also accept the
parameters 'start' and '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>
<username>root</username>. The script should accept <literal>start</literal> and
<literal>stop</literal> parameters. At startup time the
system scripts will execute the command</para>
<programlisting>/usr/local/etc/rc.d/supermailer.sh start</programlisting>
<para>which you can also use to manually start the server. At
shutdown time, the system scripts will use the
<literal>stop</literal> option, running the command</para>
<programlisting>/usr/local/etc/rc.d/supermailer.sh start</programlisting>
<para>which you can also use to manually stop the server
while the system is running.</para>
</sect3>
@ -613,13 +621,13 @@ postmaster@example.com postmaster@noc.example.net
(including 4.6-RELEASE and later)</title>
<para>With later versions of FreeBSD, you can use the
above method or you can also set</para>
above method or you can set</para>
<programlisting>mta_start_script="filename"</programlisting>
<para>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
script that you want executed at boot to start your
MTA.</para>
</sect3>
@ -630,11 +638,12 @@ postmaster@example.com postmaster@noc.example.net
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>
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 sendmail.</para>
<para>Therefore, if you are using an alternative mailer,
you will need to make sure that software trying to execute
@ -656,17 +665,17 @@ hoststat /usr/libexec/sendmail/sendmail
purgestat /usr/libexec/sendmail/sendmail</programlisting>
<para>This means that when any of these common commands
are run, such as <filename>/usr/bin/sendmail</filename>
the program that is actually sitting in that location
(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 system utilities
are run.</para>
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 sendmail, you would change
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
@ -681,12 +690,12 @@ purgestat /usr/local/supermailer/bin/purgestat-compat</programlisting>
<sect2>
<title>Finishing</title>
<para>Once you have everything configured how you want it, you should
<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 you should reboot your machine. Rebooting will also
software, or simply reboot. Rebooting will also
give you the opportunity to ensure that you have correctly
configured your machine to start your new MTA on boot.</para>
configured your system to start your new MTA automatically on boot.</para>
</sect2>
</sect1>
@ -801,13 +810,13 @@ to /etc/mail/sendmail.cf.</programlisting>
<para>Only one host should be specified as the final recipient
(add <literal>Cw bigco.com</literal> in
<filename>/etc/mail/sendmail.cf</filename> on bigco.com).</para>
<filename>/etc/mail/sendmail.cf</filename> on <hostid role="domainname">bigco.com</hostid>).</para>
<para>When the senders' <command>sendmail</command> is trying to
<para>When the sending <command>sendmail</command> is trying to
deliver the mail it will try to connect to you over the modem
link. It will most likely time out because you are not online.
<command>sendmail</command> will automatically deliver it to the
secondary MX site, i.e., your Internet provider. The secondary MX
secondary MX site, i.e. your Internet provider. The secondary MX
site will try every
(<literal>sendmail_flags = -bd -q15m</literal> in
<filename>/etc/rc.conf</filename>) 15 minutes to connect to
@ -869,7 +878,7 @@ the DNS for <quote>customer.com</quote>.</programlisting>
<answer>
<para>In default FreeBSD installations,
<application>Sendmail</application> is configured to only
<application>sendmail</application> is configured to only
send mail from the host it is running on. For example, if
a POP3 server is installed, then users will be able to
check mail from school, work, or other remote locations
@ -881,22 +890,22 @@ the DNS for <quote>customer.com</quote>.</programlisting>
message.</para>
<para>There are several ways to get around this. The most
straight forward solution is to put your ISP's address in
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" &gt; /etc/mail/relay-domains</userinput></screen>
<para>After creating this file you must restart
<para>After creating or editing this file you must restart
<application>sendmail</application>. This works great if
you are a server admin and don't 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 setup. If there are a large number of addresses
accounts set up. If there is a large number of addresses
to add, you can simply open this file in your favorite
text editor and then add the domains one per line:</para>
text editor and then add the domains, one per line:</para>
<programlisting>your.isp.example.com
other.isp.example.net
@ -904,8 +913,8 @@ users-isp.example.org
www.example.org</programlisting>
<para>Now any mail sent through your system, by any host in
this list, providing the user has an account on your
system, will succeed. This is a very nice way to allow
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>
@ -931,7 +940,7 @@ www.example.org</programlisting>
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 that specific host, there are two methods:</para>
delivered to the MTA (e.g., <application>sendmail</application>) on your own FreeBSD host, there are two methods:</para>
<itemizedlist>
<listitem>
@ -950,16 +959,16 @@ www.example.org</programlisting>
<indexterm><primary>SMTP</primary></indexterm>
<para>Regardless of which of the above you choose, in order to have
mail delivered directly to your host, you must have a permanent
(static) IP address (no dynamic PPP dial-up). If you are behind a
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 at your host itself, you need to be sure of one of two
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 MX record in your DNS points to your
<para>Make sure that the (lowest-numbered) MX record in your DNS points to your
host's IP address.</para>
</listitem>
@ -981,7 +990,8 @@ example.FreeBSD.org has address 204.216.27.XX</screen>
<para>If that is what you see, mail directly to
<email>yourlogin@example.FreeBSD.org</email> should work without
problems.</para>
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>
@ -1010,12 +1020,14 @@ 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 ends up receiving the mail in
the end while the others will queue mail temporarily if
<hostid>freefall</hostid> is busy or down.</para>
The lowest MX number is the host that receives mail directly if
available; if it's 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 the most useful. Your ISP or other
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>
@ -1023,13 +1035,13 @@ freefall MX 20 who.cdrom.com</programlisting>
<sect2 id="mail-domain">
<title>Mail for Your Domain</title>
<para>In order to set up a <quote>mailhost</quote> (a.k.a., mail
<para>In order to set up a <quote>mailhost</quote> (a.k.a. mail
server) you need to have any mail sent to various workstations
directed to it. Basically, you want to <quote>hijack</quote> any
mail for your domain (in this case <hostid
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 check their mail via POP or directly on
the server.</para>
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
@ -1037,7 +1049,7 @@ freefall MX 20 who.cdrom.com</programlisting>
<command>adduser</command> to do this.</para>
<para>The mailhost you will be using must be the designated mail
exchange for each workstation on the network. This is done in
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
@ -1048,25 +1060,25 @@ freefall MX 20 who.cdrom.com</programlisting>
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 does your DNS for you.</para>
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 the sake of an example, we
information will come in handy. For this example, we
will assume you have a customer with their own domain, in this
case <hostid role="domainname">customer1.org</hostid> and you want
case <hostid role="domainname">customer1.org</hostid>, and you want
all the mail for <hostid role="domainname">customer1.org</hostid>
sent to your mailhost, which is named <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 if you only
want to handle email for the domain.</para>
<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 this means pinging <hostid
<para>Be aware that pinging <hostid
role="domainname">customer1.org</hostid> will not work unless
an A record exists for it.</para>
</note>
@ -1082,7 +1094,7 @@ freefall MX 20 who.cdrom.com</programlisting>
<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 sendmail earlier than 8.10, the file is
a version of <application>sendmail</application> earlier than 8.10, the file is
<filename>/etc/sendmail.cw</filename>.</para>
</listitem>
@ -1090,7 +1102,7 @@ freefall MX 20 who.cdrom.com</programlisting>
<para>Add a <literal>Cwyour.host.com</literal> line to your
<filename>/etc/mail/sendmail.cf</filename> or
<filename>/etc/mail/sendmail.cf</filename> if you are using
sendmail 8.10 or higher.</para>
<application>sendmail</application> 8.10 or higher.</para>
</listitem>
</itemizedlist>
</sect2>