A real strange one.... We have joined an exchange 5.5 org and added two exchange 2000 bridgehead servers (one with a routing group connector and the other with an smtp connector) and a mailbox server to the 5.5 site. The exchange 5.5 servers are send emails to the exchange 2000 server even though it has delivered the email itself anyway! Let me explain... The exchange 5.5 server has several mailboxes that have an alternate recipients listed in the delivery options tab and the tick box is selected 'deliver to local mailbox also'. The alternate recipient is a custom recipient with an external email address. For example: Mailbox - "John Brown" - john.brown@xxxxxxxxxxx, alternate recipient "JB" Custom recipient - "JB" - JB@xxxxxxxxxxxx When a user mails John Brown the messages get delivered to him locally at domain A and externally to JB@xxxxxxxxxxxx Since the addition of the exchange 2000 servers the exchange 5.5 server does the same as above but then also tries to send this message to the E2k bridgehead server. The bridgehead server responds with an NDR (user not know) to the sender ? This is confusing the hell out of me and the senders who keep resending messages. This only happens to the users with "alternate recipient" set. Has anyone seen this before? Regards Leo