The Change Qmail-LDAP Forward SquirrelMail plugin allows users to manipulate
mailforwarding attributes in an LDAP database through a Squirrelmail plugin.
It was designed with qmail-ldap implementations in mind, but it may very well
work for other LDAP mailserver backends.  If anyone has such a server in mind,
I would be interested in hearing if it works, and/or helping to extend the
functionality of the plugin.