I've added support for SpamAssassin into vdelivermail (basically, it
will just add the SpamAssassin score of the mail if activated and
NEVER delete mail on the server).
Further, I added the -w switch to vmodinfo which has it display all
users in a domain, handy if you want to just know about them or feed
them to some scripts to do something with them (in my case, I wanted
the feature so I can set quotas for them all with xargs ;-).
Anyway, find the tarball at http://buz.ch/software.
I'd very like to hear comments and bug reports about SpamAssassin
integration (-w switch was simple enough ;-). From all I can tell,
there shouldn't be any licensing issues as the spamassassin client
stuff seems to be under the BSDL or alike license and thus can be
incorporated into GPL projects just fine.