Now, let's address the issue of webmail.example.com vs. example.com/webmail.
For those who wish to access SquirrelMail at example.com/webmail, it is necessary to add the following to Apache's configuration:
Alias /webmail /usr/share/squirrelmail
The above snippet should be added to the "Apache Directives
" field in Sites -> Website -> example.com -> Options [tab].
For those who wish to access SquirrelMail at webmail.example.com, see my posts in this thread: http://www.howtoforge.com/forums/showthread.php?t=55182