How to stop receiving mails for an account with wrong domain?

Hi!

After a lot of testing and modifying I'm stuck now and need some help:

I have a system (openSUSE 10.3) configured as a mailserver with Postfix and
Cyrus IMAP. Accounts, domains and mail addresses are kept in a MySQL
database. Sending and receiving mails is generally working.

Scenario:

There is an account "thomas" which owns the mail address "thomas@dom1.de".
There is an account "marcus" which owns the mail address "marcus@dom2.de".

Receiving mails for the specified addresses works. But:

Postfix accepts "thomas@dom2.de" and "marcus@dom1.de", too!
The received mails are delivered to the corresponding mailboxes
(user.thomas / user.marcus).

This isn't explicitly configured anywhere!
I've double-checked my database and also checked the SQL queries which are
used by Posfix (/etc/postfix/mysql-*.cf files).

How can I stop this behavior?
I'm searching for some useful configuration options etc.

Of cource, I know that it would be easier to help me if I'd also show my
main.cf... but it's a mess at the moment. I tried to many things to solve
my problem.

While I'm going to cool down and reorganize my config files, has anybody
some hints?


Thanks,
Thomas Schulte