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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta name="generator" content="HTML Tidy, see www.w3.org" /><title>Advanced Topics</title><meta name="GENERATOR" content="Modular DocBook HTML Stylesheet Version 1.7" /><link rel="HOME" title="FreeBSD Handbook" href="index.html" /><link rel="UP" title="Electronic Mail" href="mail.html" /><link rel="PREVIOUS" title="Troubleshooting" href="mail-trouble.html" /><link rel="NEXT" title="SMTP with UUCP" href="smtp-uucp.html" /><link rel="STYLESHEET" type="text/css" href="docbook.css" /></head><body class="SECT1" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#840084"alink="#0000FF"><div class="NAVHEADER"><table summary="Header navigation table" width="100%" border="0" cellpadding="0"cellspacing="0"><tr><th colspan="3" align="center">FreeBSD Handbook</th></tr><tr><td width="10%" align="left" valign="bottom"><a href="mail-trouble.html"accesskey="P">Prev</a></td><td width="80%" align="center" valign="bottom">Chapter 22 Electronic Mail</td><td width="10%" align="right" valign="bottom"><a href="smtp-uucp.html"accesskey="N">Next</a></td></tr></table><hr align="LEFT" width="100%" /></div><div class="SECT1"><h1 class="SECT1"><a id="MAIL-ADVANCED" name="MAIL-ADVANCED">22.6 AdvancedTopics</a></h1><p>The following section covers more involved topics such as mail configuration andsetting up mail for your entire domain.</p><div class="SECT2"><h2 class="SECT2"><a id="MAIL-CONFIG" name="MAIL-CONFIG">22.6.1 BasicConfiguration</a></h2><p>Out of the box, you should be able to send email to external hosts as long as you haveset up <tt class="FILENAME">/etc/resolv.conf</tt> or are running your own name server. Ifyou would like to have mail for your host delivered to the MTA (e.g., <bclass="APPLICATION">sendmail</b>) on your own FreeBSD host, there are two methods:</p><ul><li><p>Run your own name server and have your own domain. For example, <ttclass="HOSTID">FreeBSD.org</tt></p></li><li><p>Get mail delivered directly to your host. This is done by delivering mail directly tothe current DNS name for your machine. For example, <ttclass="HOSTID">example.FreeBSD.org</tt>.</p></li></ul><p>Regardless of which of the above you choose, in order to have mail delivered directlyto your host, it must have a permanent static IP address (not a dynamic address, as withmost PPP dial-up configurations). If you are behind a firewall, it must pass SMTP trafficon to you. If you want to receive mail directly at your host, you need to be sure ofeither of two things:</p><ul><li><p>Make sure that the (lowest-numbered) MX record in your DNS points to your host's IPaddress.</p></li><li><p>Make sure there is no MX entry in your DNS for your host.</p></li></ul><p>Either of the above will allow you to receive mail directly at your host.</p><p>Try this:</p><pre class="SCREEN"><samp class="PROMPT">#</samp> <kbd class="USERINPUT">hostname</kbd>example.FreeBSD.org<samp class="PROMPT">#</samp> <kbd class="USERINPUT">host example.FreeBSD.org</kbd>example.FreeBSD.org has address 204.216.27.XX</pre><p>If that is what you see, mail directly to <code class="EMAIL"><<ahref="mailto:yourlogin@example.FreeBSD.org">yourlogin@example.FreeBSD.org</a>></code>should work without problems (assuming <b class="APPLICATION">sendmail</b> is runningcorrectly on <tt class="HOSTID">example.FreeBSD.org</tt>).</p><p>If instead you see something like this:</p><pre class="SCREEN"><samp class="PROMPT">#</samp> <kbd class="USERINPUT">host example.FreeBSD.org</kbd>example.FreeBSD.org has address 204.216.27.XXexample.FreeBSD.org mail is handled (pri=10) by hub.FreeBSD.org</pre><p>All mail sent to your host (<tt class="HOSTID">example.FreeBSD.org</tt>) will end upbeing collected on <tt class="HOSTID">hub</tt> under the same username instead of beingsent directly to your host.</p><p>The above information is handled by your DNS server. The DNS record that carries mailrouting information is the <span class="emphasis"><i class="EMPHASIS">M</i></span>aile<span class="emphasis"><i class="EMPHASIS">X</i></span>change entry. If no MX recordexists, mail will be delivered directly to the host by way of its IP address.</p><p>The MX entry for <tt class="HOSTID">freefall.FreeBSD.org</tt> at one time looked likethis:</p><pre class="PROGRAMLISTING">freefall MX 30 mail.crl.netfreefall MX 40 agora.rdrop.comfreefall MX 10 freefall.FreeBSD.orgfreefall MX 20 who.cdrom.com</pre><p>As you can see, <tt class="HOSTID">freefall</tt> had many MX entries. The lowest MXnumber is the host that receives mail directly if available; if it is not accessible forsome reason, the others (sometimes called ``backup MXes'') accept messages temporarily,and pass it along when a lower-numbered host becomes available, eventually to thelowest-numbered host.</p><p>Alternate MX sites should have separate Internet connections from your own in order tobe most useful. Your ISP or another friendly site should have no problem providing thisservice for you.</p></div><div class="SECT2"><h2 class="SECT2"><a id="MAIL-DOMAIN" name="MAIL-DOMAIN">22.6.2 Mail for YourDomain</a></h2><p>In order to set up a ``mailhost'' (a.k.a. mail server) you need to have any mail sentto various workstations directed to it. Basically, you want to ``claim'' any mail for anyhostname in your domain (in this case <tt class="HOSTID">*.FreeBSD.org</tt>) and divertit to your mail server so your users can receive their mail on the master mailserver.</p><p>To make life easiest, a user account with the same <span class="emphasis"><iclass="EMPHASIS">username</i></span> should exist on both machines. Use <ahref="http://www.FreeBSD.org/cgi/man.cgi?query=adduser&sektion=8"><spanclass="CITEREFENTRY"><span class="REFENTRYTITLE">adduser</span>(8)</span></a> to dothis.</p><p>The mailhost you will be using must be the designated mail exchanger for eachworkstation on the network. This is done in your DNS configuration like so:</p><pre class="PROGRAMLISTING">example.FreeBSD.org A 204.216.27.XX ; Workstation MX 10 hub.FreeBSD.org ; Mailhost</pre><p>This will redirect mail for the workstation to the mailhost no matter where the Arecord points. The mail is sent to the MX host.</p><p>You cannot do this yourself unless you are running a DNS server. If you are not, orcannot run your own DNS server, talk to your ISP or whoever provides your DNS.</p><p>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<tt class="HOSTID">customer1.org</tt>, and you want all the mail for <ttclass="HOSTID">customer1.org</tt> sent to your mailhost, <ttclass="HOSTID">mail.myhost.com</tt>. The entry in your DNS should look like this:</p><pre class="PROGRAMLISTING">customer1.org MX 10 mail.myhost.com</pre><p>You do <span class="emphasis"><i class="EMPHASIS">not</i></span> need an A record for<tt class="HOSTID">customer1.org</tt> if you only want to handle email for thatdomain.</p><div class="NOTE"><blockquote class="NOTE"><p><b>Note:</b> Be aware that pinging <tt class="HOSTID">customer1.org</tt> will not workunless an A record exists for it.</p></blockquote></div><p>The last thing that you must do is tell <b class="APPLICATION">sendmail</b> on yourmailhost what domains and/or hostnames it should be accepting mail for. There are a fewdifferent ways this can be done. Either of the following will work:</p><ul><li><p>Add the hosts to your <tt class="FILENAME">/etc/mail/local-host-names</tt> file if youare using the <var class="LITERAL">FEATURE(use_cw_file)</var>. If you are using a versionof <b class="APPLICATION">sendmail</b> earlier than 8.10, the file is <ttclass="FILENAME">/etc/sendmail.cw</tt>.</p></li><li><p>Add a <var class="LITERAL">Cwyour.host.com</var> line to your <ttclass="FILENAME">/etc/sendmail.cf</tt> or <tt class="FILENAME">/etc/mail/sendmail.cf</tt>if you are using <b class="APPLICATION">sendmail</b> 8.10 or higher.</p></li></ul></div></div><div class="NAVFOOTER"><hr align="LEFT" width="100%" /><table summary="Footer navigation table" width="100%" border="0" cellpadding="0"cellspacing="0"><tr><td width="33%" align="left" valign="top"><a href="mail-trouble.html"accesskey="P">Prev</a></td><td width="34%" align="center" valign="top"><a href="index.html"accesskey="H">Home</a></td><td width="33%" align="right" valign="top"><a href="smtp-uucp.html"accesskey="N">Next</a></td></tr><tr><td width="33%" align="left" valign="top">Troubleshooting</td><td width="34%" align="center" valign="top"><a href="mail.html" accesskey="U">Up</a></td><td width="33%" align="right" valign="top">SMTP with UUCP</td></tr></table></div><p align="center"><small>This, and other documents, can be downloaded from <ahref="ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/">ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/</a>.</small></p><p align="center"><small>For questions about FreeBSD, read the <ahref="http://www.FreeBSD.org/docs.html">documentation</a> before contacting <<ahref="mailto:questions@FreeBSD.org">questions@FreeBSD.org</a>>.<br />For questions about this documentation, e-mail <<ahref="mailto:doc@FreeBSD.org">doc@FreeBSD.org</a>>.</small></p></body></html>⌨️ 快捷键说明
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