- Various rewording/addition in DNS part (how to check a MX for
example). - Update an sendmail FAQ excerpt PR: docs/64648 Submitted by: Marc Silver <marcs@draenor.org>
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1 changed files with 60 additions and 32 deletions
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@ -171,27 +171,42 @@
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<secondary><application>exim</application></secondary>
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</indexterm>
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<para>This is usually <application>sendmail</application> (by
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default with FreeBSD) or one of the other mail server daemons such
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as <application>qmail</application>,
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<application>postfix</application>, or
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<application>exim</application>. There are others, but those are
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the most widely used.</para>
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<para>&os; ships with <application>sendmail</application> by
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default, but also support numerous other mail server daemons,
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just some of which include:</para>
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<para>The server daemon usually has two functions—it looks
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after receiving incoming mail and delivers outgoing mail. It is
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not responsible for allowing you to collect mail using protocols
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<itemizedlist>
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<listitem>
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<para><application>exim</application>;</para>
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</listitem>
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<listitem>
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<para><application>postfix</application>;</para>
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</listitem>
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<listitem>
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<para><application>qmail</application>.</para>
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</listitem>
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</itemizedlist>
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<para>The server daemon usually has two functions—it is responsible
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for receiving incoming mail as well as delivering outgoing mail. It is
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<emphasis>not</emphasis> responsible for the collection of mail using protocols
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such as <acronym>POP</acronym> or <acronym>IMAP</acronym> to
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read your email, nor does it allow connecting to local
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<filename>mbox</filename> or Maildir mailboxes. You may require
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an additional <link linkend="mail-receive">daemon</link> for
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that.</para>
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<para>Be aware that some older versions of
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<application>sendmail</application> have some serious security
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problems, however as long as you run a current version of it you
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should not have any problems. As always, it is a good idea to
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stay up-to-date with any software you run.</para>
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<warning>
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<para>Older versions of <application>sendmail</application>
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have some serious security issues which may result in an
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attacker gaining local and/or remote access to your machine.
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Make sure that you are running a current version to avoid
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these problems. Optionally, install an alternative
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<acronym>MTA</acronym> from the <link linkend="ports">&os;
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Ports Collection</link>.</para>
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</warning>
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</sect2>
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<sect2 id="mail-dns">
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@ -200,15 +215,25 @@
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<para>The Domain Name System (DNS) and its daemon
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<command>named</command> play a large role in the delivery of
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email. In order to deliver mail from your site to another, the
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server daemon will look up the site in the DNS to determine the
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host that will receive mail for the destination.</para>
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server daemon will look up the remote site in the DNS to determine the
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host that will receive mail for the destination. This process
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also occurs when mail is sent from a remote host to your mail
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server.</para>
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<para>It works the same way when you have mail sent to you. The DNS
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contains the database mapping hostname to an IP address, and a
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hostname to mailhost. The IP address is specified in an A record.
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The MX (Mail eXchanger) record specifies the mailhost that will
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receive mail for you. If you do not have an MX record for your
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hostname, the mail will be delivered directly to your host.</para>
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<para><acronym>DNS</acronym> is responsible for mapping
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hostnames to IP addresses, as well as for storing information
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specific to mail delivery, known as MX records. The MX (Mail
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eXchanger) record specifies which host, or hosts, will recieve
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mail for a particular domain. If you do not have an MX record
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for your hostname or domain, the mail will be delivered
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directly to your host provided you have an A record pointing
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your hostname to your IP address.</para>
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<para>You may view the MX records for any domain by using the
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&man.host.1; command, as seen in the example below:</para>
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<screen>&prompt.user; <userinput>host -t mx FreeBSD.org</userinput>
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FreeBSD.org mail is handled (pri=10) by mx1.FreeBSD.org</screen>
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</sect2>
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<sect2 id="mail-receive">
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@ -219,13 +244,15 @@
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</indexterm>
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<para>Receiving mail for your domain is done by the mail host. It
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will collect mail sent to you and store it for reading or pickup
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in either <filename>mbox</filename> or Maildir format, depending
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on your configuration. Mail can then be remotely accessed using
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either <acronym>POP</acronym> or <acronym>IMAP</acronym>, or
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alternatively by using a mail user agent that is locally
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installed on the mail host itself which will directly
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communicate with the mailbox. This means that should you only
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will collect all mail sent to your domain and store it
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either in <filename>mbox</filename> (the default method for storing mail) or Maildir format, depending
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on your configuration.
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Once mail has been stored, it may either be read locally using
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applications such as &man.mail.1; or
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<application>mutt</application>, or remotely accessed and
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collected using protocols such as
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<acronym>POP</acronym> or <acronym>IMAP</acronym>.
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This means that should you only
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wish to read mail locally, you are not required to install a
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<acronym>POP</acronym> or <acronym>IMAP</acronym> server.</para>
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@ -327,7 +354,7 @@
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<para>Mailboxes may be accessed locally by directly utilizing
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<acronym>MUA</acronym>'s on the server on which the mailbox
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resides. This can be done using applications such as
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<application>mutt</application> or <command>mail</command>.
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<application>mutt</application> or &man.mail.1;.
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</para>
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</sect3>
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</sect2>
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@ -911,9 +938,9 @@ purgestat /usr/local/supermailer/bin/purgestat-compat</programlisting>
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<para>This is answered in the
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<application>sendmail</application> FAQ as follows:</para>
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<programlisting>I am getting <quote>Local configuration error</quote> messages, such as:
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<programlisting>I'm getting these error messages:
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553 relay.domain.net config error: mail loops back to myself
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553 MX list for domain.net points back to relay.domain.net
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554 <user@domain.net>... Local configuration error
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How can I solve this problem?
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@ -922,6 +949,7 @@ You have asked mail to the domain (e.g., domain.net) to be
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forwarded to a specific host (in this case, relay.domain.net)
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by using an MX record, but the relay machine does not recognize
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itself as domain.net. Add domain.net to /etc/mail/local-host-names
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[known as /etc/sendmail.cw prior to version 8.10]
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(if you are using FEATURE(use_cw_file)) or add <quote>Cw domain.net</quote>
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to /etc/mail/sendmail.cf.</programlisting>
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