Cross Domain Administration Process does not work anymore

Hi I have a very strange problem:

My cross domain Create Replica using adminp does not work anymore. The 1st server sends the request to the other domain’s server BUT that one sais “Recipient in local Internet Domain not found, forwarding to Smart Host” and my “Administration Requests@DOMAIN” mail hangs in the Mailbox till it is dead.

Any ideas?

We use a smarthost for SMTP mails.

Thanks

Ben