I have added a new Exchange 2003 server to an existing Exchange 5.5
organization. Any new or migrated mailbox on the Exchange 2003 cannot send
messages back to mailboxes that reside on the Exchange 5.5 server. An NDR is
immediately returned stating "The e-mail address could not be found. Perhaps
the recipient moved to a different e-mail organization, or there was a
mistake in the address. Check the address and try again."
However, messages can be sent from mailboxes on the Exchange 5.5 server to
recipients on the Exchange 2003 server.
I found the KB article (836563) which shows these symptoms, however it did
not apply to this situation. My Exchange 5.5 server does not contain a dot in
the server name.
Any suggestions would be appreciated.