Forward Unresolved to Sendmail Stacks messages up in queue

[kernow]

I'm currently in the process of migrating from Sendmail to Exchange 2000.
I've changed our MX record to point to the Exchange server and enabled the Forward Unresolved Recipients to the IP address of the old Sendmail server.
The IP has been entered in square brackets as per a MS KB doc I saw like so [1.1.1.1]
My problem is that the unresolved mail just stacks up in the queue on the Exchange server. The resolvable mail for the users that have been migrated works fine.
The server has Windows 2000 Advanced Server SP3 and Exchange 2000 SP 3 installed.
Does anyone have any ideas on this?
Thanks in advance.

 

[kernow]

We've found a solution to the problem - MS have a Q article on it:

http://support.microsoft.com/default.aspx?scid=kb;en-us;319759

Forward unresolved recipients doesn't work - you have to use a shared SMTP domain name space.

Hope this is of help to someone else in the future.

Regards.