Much progress made.

I've found several references to this issue by googling my error below, and have moved through the related files/dirs and set all users to my designated user, plus setuid and gid on maildrop, and the errors stopped. However, the filter still wasn't being used.

I am using a virtual system, and have the directories arranged as follows, using my test account rbra...@amd64.csd-bes.net:

/var/spool/postfix/virtual/amd64.csd-bes/rbrandt

with the usual /cur, /new, /tmp, /.Trash, /.Drafts directories therein. Also in that folder I had the .mailfilter file, set up to deliver mail with a specified Subject header "[test]" into the /.test directory. As I said above, that doesn't work. Assuming that maildrop was working but not finding a mailfilter, I moved that file up the directory tree; lo, and behold, it works at /var/spool/postfix/virtual/.mailfilter!

This is great news, obviously, since I know that it is essentially working at this point. But the whole point here is to have a .mailfilter for each virtual user. I think I understand why it's looking there: the maildrop docs say that it looks for .mailfilter at $HOME/.mailfilter, and in the MySQL database I have home set to /var/spool/postfix/virtual, so that's where maildrop is looking for .mailfilter. The maildir value is "amd64.csd-bes.net/rbrandt/. I suppose I could set home to be the complete path /var/spool/postfix/virtual/amd64.csd-bes/rbrandt/, leaving the maildir value empty, but that doesn't seem "right" to me. What would be the purpose of the maildir value then? And it prevents me from setting a default value for home that will be the same for each user record I add.

So are there any better ways?

Thanks for all your help you guys. Gotta love the Dutch. :)

Rob