Remove a domain from Exchange 2003, now other domains cannot send to the old domain error 5.1.1

We have a single Exchange 2003 server.  We have multiple mail domains on the server, but are slowly moving to a hosted email solution.  I moved the first domain, I will call itdomainABC, to our hosted solution.  I have removed all exchange mailboxes from the users, and deselected the domain from Recipient Policies.  I then ran the policy.  

Whenever I send an email to anyone on Domain ABC from any other domain on the Exchange server, I get the 5.1.1 message.  I am not sure what to do next - any help would be appreciated...

Brian