I've been beating my head against a wall for a while now on this one. Basically, here is the rundown:

Our MX record points to a frontend SMTP server, which contains aliases for actually routing the mail. No alias, no access to the backend storage server, which is what our clients connect to.

I'm upgrading the backend email server. Currently, a user is created for every email user on the server, which creates the mailbox. On the new server, everything autheticates through PAM to an LDAP server (all of which is working properly). My goal is to get Postfix to create the Maildir directory for the user automatically. This works fine when I have the /home directory with 777 permissions, but for obvious reasons, this should be avoided. I would like to do this with 775 permissions on /home with a group owner of whatever user Postfix is running as, but I can't seem to figure out what user to use. With the 777 permissions, the /home/$user/Maildir directory is created on message delivery. Does anybody know how I can do this without 777 permissions?

The system I am working on is a 64-bit Debian Lenny 5.07 install.

Any advice would be appreciated.