Here is a strange one, I have a client that has a AD Domain apples.com, which moved to a new company, I set up exchange 2003 and added relay access for the new email domain called oranges.com I and everybody from the outside can send to oranges.com but oranges.com cannot email me, they have no problem sending to anyone except for me and here is the bounce back error.
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<apples_Srv.apples.com #5.5.0 smtp;550-Verification failed for <Administrator@oranges.com>>
Windows 2000 Server, Exchange 2003.
any thoughts on this one.