I have just added a an exchange 2007 server to my exchange group which has an exchange 2003 server.
I have moved a test mailbox to the new-2007 server.
Some transports work from mailboxes
I can send successfully mail from
M-box on new-2007 to MBox on new-2007
M-box on new-2007 to MBox on old-2003
external email to MBox on old-2003
But failing is
M-box on old-2003 to MBox on new-2007
external email to MBox on new-2007
Anyone got any pointers - highly appreciated.