Catchall with UserDB?

[Ferenc]

Hi!

I've set up Postfix with virtual users. I wanted to get Dovecot and LMTP up and running with
Passwd-file UserDB, which they do, but I can't figure out how to make use of a catch-all.

Currently, mail to joe at example.com needs Joe to be in the Passwd-file. I would like
anyone at example.com to go to Joe's mailbox, or actually mail to @example.com should go to Joe. But
what do I put in the Passwd-file? 

I need this for several domains. Like @somedomain.org should go to jim at example.com and
@anydomain.net to jake at example.com. I've googled myself silly but I cannot find the it. Everybody
is hooked on a sql userdb which seems like overkill to me. With Postfix doing local delivery this
is rather trivial. With Dovecot LDA I got it working by using virtual_alias_maps and the right
parameters in master.cf. But with LMTP I'm stumped.

cheers,
Ferenc