I am trying to get dovecot to work on a system that uses qmail as its MTA. As is typical on such systems, the user's primary inbox is an mbox file called Mailbox, in their home directory. Global shell config files /etc/csh.cshrc and /etc/profile set the MAIL environment variable to ~/Mailbox for the users, which is enough to satisfy their interactive mail clients such as pine, mutt, and elm.

The mail-storages.txt file in the dovecot docs seems to say that dovecot will not have a problem with this kind of setup. However, I can't figure out how to make it work. The MAIL variable is only set for users who are using shells like tcsh, bash, etc. The server apparently does not operate in a shell, so it is looking in some other location, perhaps /var/mail/$USER, so everyone's INBOX appears to be empty.

It would help if mail-storages.txt, when referring to environment variables such as MAIL, would clarify *whose* environment variables are being referred to. Is it the environment of the user who built dovecot? Is it the environment of the user running the main dovecot process? Is it the environment of the user who is checking their mail / the user that dovecot runs setuid as? When and where do I set the MAIL variable so that dovecot will see it? Or is there some other problem?

Any help appreciated...