relaydelay: wave goodbye

The article discusses a specific option for puremagic's greylisting.

- It tells users to install mysql40-server and perl5.16; neither of
  which exist any more.

- The last edit was 2015, by me, to switch from `pkg_add` to `pkg`.

- It encourages users to download code from a third-party website,
  without validation, via HTTP (not even HTTPS).

- The code itself has to be patched to compile

and more generally the FreeBSD project is not in the business of
teaching end users how to run an anti-spam mail server.

Discussed with:	allanjude

en_US.ISO8859-1/htdocs/docs/books.xml

@@ -232,12 +232,6 @@
       A guide to writing new rc.d scripts and understanding those
       already written.</p>
 
-    <p><a href="&url.articles;/relaydelay/index.html">FreeBSD as a
-	greylist mail server</a> (relaydelay)<br/>
-      Implementing a greylist mail server on FreeBSD using Sendmail,
-      MySQL, Perl and the relaydelay software.  This is an excellent
-      method to use in the fight against spam.</p>
-
     <p><a href="&url.articles;/releng/index.html">FreeBSD Release
 	Engineering</a> (releng)<br/>
       Describes the approach used by the FreeBSD release engineering