[Dovecot] Static list of users with passdb pam

Hi,

On my system, I want to provide imap access for some of the users listed in /etc/passwd. The list of users should be provided by me, and should just be a list in a text file. All the userdb options are static (uid, gid, home directory). Unfortunately, I cannot think of a way to configure Dovecot to do this. The closest I get is with:

passdb pam {} userdb passwd-file { args = /path/to/passwd-file }

However, the passwd-file is now more complex than it really needs to be, as it includes fields for password, uid, gid and home directory as well.

Is there some way to handle this? Or am I trying to do something stupid?

Thanks!

Koen