[Dovecot] postfix + dovecot lda,

I'm trying to replace procmail with deliver but I'm having problems with the group part of things. I keep getting:

Aug 29 16:44:19 dingbat deliver(mimo): open(/var/mail/.temp.dingbat.3969.d1689935a308e0dd) failed: Permission denied Aug 29 16:44:19 dingbat deliver(mimo): file_lock_dotlock() failed with mbox file /var/mail/mimo: Permission denied

My primary group is mimo and I think it's trying to use that. I changed it to mail and things work. But I do not want all my users to have a primary group mail.

Is there a way I can force deliver to use group mail as group and ignore the per user gid?

I tried chmod 6755 /usr/lib/dovecot/deliver but no change.

This is on debian/etch, help appreciated....

mimo