[Dovecot] pgsql configuration

[Tom Allison]

from the pgsql configuration file:
# Query to retrieve the password.
#
# The query should return one row, one column. If more than one row or 
column
# is returned, authentication will automatically fail.
#
# Available substitutions:
#   %u = entire userid
#   %n = user part of user at domain
#   %d = domain part of user at domain
#

# Query to retrieve the user information.
#
# The query must return only one row. The columns to return are:
#   home - Home directory
#   mail - MAIL environment
#   system_user - System user name (for getting user's groups from 
/etc/group)
#   uid - System UID
#   gid - System GID
#
# Either home or mail is required. uid and gid are required. If more 
than one
# row is returned or there's missing fields, login will automatically fail.
#


I'm a bit slow here, so if someone could just nod if I'm in the right 
direction:

I want to support IMAP for at least two domains.
Therefore I have to use the authentication string of:
SELECT password FROM users WHERE userid = '%u'
and the user must enter their entire email address for their login name.
(I can do this!)

I want some portion of these domains and users to be consistent with 
existing accounts in my /etc/passwd database.  I don't expect to use 
passwd information for the username and password, but I want the 
information returned for joe at domain2.com to be for the user:joe in my 
passwd file and have his email in /home/joe/Maildir.
Similarly, I want others (either fred at domain2.com or jane at domain1.com) 
to be (ideally) all driven under a non-local account name and login.

For this second one, I'm thinking I need to do something like this in 
the user information query (this is mostly a guess):
for joe at domain2.com (/etc/passwd) :: jane at domain1.com (no passwd)
home - /home/joe  --or-- can I use ~/ :: /var/spool/imap/%d/%n  ??
mail - maildir:~/Maildir  ::  maildir:/var/spool/imap/%d/%n ??
system_user - joe :: (a guess -- adduser dovecot-imap to passwd maybe)
uid - joes uid (1002) ::  dovecot-imap uid (510)
gid - joes gid (1001) ::  dovecot-imap gid (510) with seperate group

This is where I get fuzzy.  If someone could help me figure out where I 
went wrong I would appreciate it.

If I did this correctly, then in theory I could pass email delivery to 
procmail and have one set of rules (/etc/procmail) do some additional 
filtering for all the email under my domain1.com (spam filtering mostly) 
and perform a final delivery to maildirs in 
/var/spool/imap/doamin1.com/jane/

Or am I sleep deprived?