Outlook sort/file Rules based on the TO: SMTP address

[Roman]

Hello,
This might seem a bit longish: We has set-up a single mailbox for HR to
recieve resumes from candidates. Mailbox has a number of Email addresses
assigned to it in exchange 2003 i.e. (e-mail address removed);
(e-mail address removed) etc.
In Outlook 2003 we have set-up rules in Outlook 2003 that sort/file the
incoming messages according to SMTP address. So for instance, a message sent
to (e-mail address removed) wll be moved into Position1 folder in mailbox.
At one point this setup was working great but recently the rules in outlook
don't seem to be working. The incoming messages get filed into every single
folder that is out there on Outlook. So the message that was sent to
(e-mail address removed) is ending up in Position1, Position2, Position3, etc.
folders. We have only about 6 or 7 positions open, hence there are only 6 or
7 rules in outlook...
So my question is
How do Outlook rules resolve the "Message sent To..." address via MAPI or
does it actually check the SMTP address..
The environment: Exchange 2003 latest SP & Outlook 2003 SP2

Thanks in advance