Document the correct use of rc.conf

sendmail_enable="" variable for 5.X
and later.

Reviewed by:	csjp
Submitted by:	lawrance
Approved by:	trhodes (mentor)

en_US.ISO8859-1/books/handbook/mail/chapter.sgml

@@ -699,13 +699,30 @@ postmaster@example.com          postmaster@noc.example.net
 	chosen.</para>
     </sect2>
 
-    <sect2>
+    <sect2 id="mail-disable-sendmail">
       <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
+	between 4.5-RELEASE, 4.6-RELEASE, and later releases.
-	used to disable it is subtly different.</para>
+	Therefore, the procedure used to disable it is subtly
+	different.</para>
+
+	<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>
 
       <sect3>
 	<title>FreeBSD 4.5-STABLE before 2002/4/4 and Earlier
@@ -727,26 +744,36 @@ postmaster@example.com          postmaster@noc.example.net
 	  (Including 4.6-RELEASE and Later)</title>
 
 	<para>In order to completely disable
-	  <application>sendmail</application> you must use</para>
+	  <application>sendmail</application>, including the outgoing
+	  mail service, you must use</para>
 
 	  <programlisting>sendmail_enable="NONE"</programlisting>
 
 	  <para>in <filename>/etc/rc.conf.</filename></para>
 
-	<warning>
+	<para>If you only want to disable
-	  <para>If you disable <application>sendmail</application>'s
+	  <application>sendmail</application>'s incoming mail service,
-	    outgoing mail service in this way, it is important that you
+	  you should set</para>
-	    replace it with a fully working alternative mail delivery
+
-	    system.  If you choose not to, system functions such as
+	  <programlisting>sendmail_enable="NO"</programlisting>
-	    &man.periodic.8; will be unable to deliver their results by
+
-	    e-mail as they would normally expect to.  Many parts of your
+	<para>in <filename>/etc/rc.conf</filename>.  However, if
-	    system may expect to have a functional
+	  incoming mail is disabled, local delivery will still
-	    <application>sendmail</application>-compatible system.  If
+	  function.  More information on 
-	    applications continue to use
+	  <application>sendmail</application>'s startup options is
-	    <application>sendmail</application>'s binaries to try to send
+	  available from the &man.rc.sendmail.8; manual page.</para>
-	    e-mail after you have disabled them, mail could go into an
+      </sect3>
-	    inactive <application>sendmail</application> queue, and never be delivered.</para>
+
-	</warning>
+      <sect3>
+	<title>FreeBSD 5.0-STABLE and Later</title>
+
+	<para>In order to completely disable
+	  <application>sendmail</application>, including the outgoing
+	  mail service, you must use</para>
+
+	  <programlisting>sendmail_enable="NONE"</programlisting>
+
+	  <para>in <filename>/etc/rc.conf.</filename></para>
 
 	<para>If you only want to disable
 	  <application>sendmail</application>'s incoming mail service,
@@ -1497,9 +1524,9 @@ hostname=_HOSTNAME_</programlisting>
       this the <quote>outgoing mail server</quote> or
       <quote>SMTP server</quote>).</para>
 
-    <para>Make sure you disable <application>sendmail</application> by
+    <para>Make sure you disable <application>sendmail</application>,
-      setting <literal>sendmail_enable="NONE"</literal>
+      including the outgoing mail service. See
-      in <filename>/etc/rc.conf</filename>.</para>
+      <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