I inherited an exchange 2003 setup with an exchange 2010 migration that looks half complete.
I can move mailboxes to the new server but users on the old server are unable to send email outside the domain. . I am not sure what hasn't been completed on the migration.
I have a test mailbox moved to the 2010 exchange server. It doesnt' send email and users that are on the 2003 box can't send email either. outside the domain that is. I am sure there is something missing.
AD looks to be in good shape.