I have started a 2003 - 2010 Exchange migration. I have moved a handful of mailboxes to 2010, and now those mailboxes cannot email internally to those who still have mailboxes on 2003. The email sits in the SMTPRelaytoTiRg queue on the 2010 box. When I ran the Exchange Mail Flow troubleshooter, it reported "Remote server failed the mail acceptance test. BDAT command Respond=Remote socket is not available." I have checked everything I can think of, and can't figure out what is wrong. To make things weirder, earlier today the queue cleared out on its own and the mail was delivered. But now it is building back up again. Help!