Update the list of reasons why mail to FreeBSD.org may be rejected.

Inspired by: 	spamfest on -questions
Approved by:	murray

en_US.ISO8859-1/books/faq/book.sgml

@@ -11182,7 +11182,8 @@ raisechar=^^</programlisting>
         </question>
 
         <answer>
-	  <para>The FreeBSD.org mail system rejects mail that is
+	  <para>The FreeBSD.org mail system implements some of the
+	    stricter Postfix checks on incoming mail and rejects mail that is
             either misconfigured or is potential spam.  Your mail
             might bounce for one of the following reasons:</para>
 
@@ -11217,6 +11218,27 @@ raisechar=^^</programlisting>
                 option.  In this case, relay your email through your
                 service provider's mail server.</para>
             </listitem>
+
+	    <listitem>
+	      <para>The hostname given in the EHLO/HELO part of the SMTP
+		exchange cannot be resolved to an IP address.</para>
+
+	      <para>A fully qualified, resolvable host name is necessary
+		in this part of the SMTP dialogue before mail will be
+		accepted.  If you do not have a host name that is registered
+		in the DNS, then you should use your service provider's mail
+		server to relay your mail.</para>
+	    </listitem>
+
+	    <listitem>
+	      <para>Your message had a message ID ending with the string
+		<quote>localhost</quote>.</para>
+
+	      <para>Some mail user agents generate bad message IDs which will
+		not be accepted.  You will need to persuade your mail user
+		agent to generate a valid message ID or else configure your
+		mail transfer agent to rewrite them.</para>
+	    </listitem>
           </itemizedlist>
         </answer>
       </qandaentry>