We are in the middle of an Exchange migration from 2003 to 2010. We have a test mailbox on Exchange 2010. The test account can send email to world and to all mailboxes on 2003. The problem is the 2003 users are not able to reply or send email to the test user. The 2003 user emails sent to 2010 test user, queue up in "messages with an unreachable destination" on 2003 server
Some information that may be relevant...
Default SMTP Virtual Server sends email to a smart-host
BCEXCH - is exchange 2003 cluster
BC-PHX-EXCH01 - Exchange 2010
BC-PHX-EXCH02 - Exchange 2010
Both 2010 servers are in a DAG
Your help would be greatly appreciated.