I just finished hacking SpamAssassin support into vdelivermail.
Basically, you need to have the spamd Daemon of the spamassassin
package running on port 783 (standard port for it) thru which all
messages smaller than 300k are "filtered" which means they get the
SpamAssassin score (and nothing else!) added to their headers like:
By default, the "filtering" is turned off so people who don't want
to use it won't note much difference. For the others, if spamd isn't
running, all messages will get delivered unchanged.
To enable the functionality, pass --enable-spamassassing=y to
There's one remaining bug: the size parameter of Maildir++ won't get
updated accordingly, I suppose this could be solved by stat()ing the
file at the end and then renaming it, thoughts?
Anyway, you can get the tarball at http://www.buz.ch/software