Hi there,
Other auth modules (eg passwd-file) allow a username_format to be specified, but not the PAM module.
The use-case, is where I want a static userdb configuration which takes the domain into account but still want to use PAM for authentication, eg:
userdb { driver = static args = uid=8 gid=12 home=/mnt/storage/mail/vhosts/%d/%n }
passdb { driver = pam args = username_format=%n allow_pam_transform=no dovecot }
The global "auth_username_format" setting ends up changing the username, so looses the ability to have different mailboxes based on domain.
There is also a new setting, allow_pam_transform which stops the username being changed after a successful authentication. Normally, if PAM changes the username, then dovecot must update its record of the username for further processing - but in this use case we must disable this function.
-- Brad.