Hi Timo, currently superadmins can be configured in dovecot i.e in mysql as "superadmins" this means the can log in in any mailbox on the server this is a very nice feature in real world scenarios specially for support people
in postfixadmin i.e there are also defined domainadmins ( this is for delegate usermail creation/delete etc in the postfixadmingui ) in mysql
it would be nice to have or simply use postfixadmins mysql domainadmins in mysql table entries to login for domainadmins only login to mailboxes of their related maildomain this would be also massiv helpfull for postmasters/support people in a full virtual setup
perhaps you might get this in dovecot 1.2 before closing at beta stage
-- Best Regards
MfG Robert Schetterer
Germany/Munich/Bavaria