We have just installed a new exchange server into our domain, moved all the mailboxes to the new server and then changed the IP address of the old server so that we could move the new servers ip into place for a clean swap over (IP wise)
When we do this only about half of the external mail sent to the server is passed to the mailboxes however if we place the old server back on the IP address it relays all the mail to the new server.
All SMTP Connection and relay settings are the same.
Can any one think of a reason for this strange response?