I am attempting to do a special configuration of my mail system to spam filter messages sent to a Mailman mailing list. I need to be able to pipe the emial the mailman as the mailman group. My configuration is:

Postfix/courier-imap/MySQL authentication/maildrop/Mailman.

Normally, messages sent to a Mailman mailing list are sent to an alias that is then piped to the mailman program. I want instead to process the mail as if it were sent to a real user, with that user's maildrop mail filter file then piping the email to mailman. By using the mail filter, I can route the email first through smamassassin using xfilter, then send it on to the mailman program.

So I have a simple filter file as:

xfilter "/usr/bin/spamassassin -x"

to "|/usr/local/mailman/mail/mailman post mymaillist"

When I send a message to the mailing list, I get a message:

" The Postfix program

<myma...@domain.com>: Command died with status 2: "/usr/local/bin/maildrop". Command output: Failed to create default user preference file /var/spool/postfix/virtual/.spamassassin/user_prefs Group mismatch error. Mailman expected the mail wrapper script to be executed as group "mailman", but the system's mail server executed the mail script as group "csdbes". Try tweaking the mail server to run the script as group "mailman", or re-run configure, providing the command line option `--with-mail-gid=csdbes'."

Of course, I don't get this error on any other list so the advice of tweaking mailman isn't appropriate. What I need to do is be able to specify the group when piping the email. Can this be done?

Actually, one thing I don't understand is why piping from Postfix works, but from maildrop does not. The postfix alias pipe does not contain any arguments specifying a user group, and is running as it's own user and group, yet doesn't produce errors. If anyone knows, I'd appreciate letting me know.

Rob