Adrian Zaugg writes:

How can I configure the auto create mailbox feature that it works and let run LMTP and IMAP process as user %u and group mail and let create the mailboxes in /var/mail as (example user tester) with the following permissions:

/var/mail:

drwxrwx--x root mail 3072 Dec 18 01:43 . drwx------ tester tester 1024 Jan 09 12:53 tester

This is probably what you need:

# Group to enable temporarily for privileged operations. Currently this is
# used only with INBOX when either its initial creation or dotlocking fails.
# Typically this is set to "mail" to give access to /var/mail.
mail_privileged_group = mail

...or do I need a different approach?

You could also

chmod 1777 /var/mail

but this will allow arbitrary uses who have filesystem access to create their own files here, and maybe DoS a new user from being created (or maybe even anticipate a new mailbox, create one with mode 0777 and wait to intercept mail?).

Joseph Tam <jtam.home@gmail.com>