Hello, I have a forwarder setup on a mailbox user1.to a@abc.com I have a sent connector, any email to abc.com will be sent to smart host 10.10.10.10.which will try sending for 2 days if 10.10.10.10 is unavailable. My question is if 10.10.10.10 is down for 2 days & A has sent email to user1 , who will receive NDR user1 or original sender A. Feel free to ask for any confusion for any confusion.

A@abc.com is an external user sending a mail to an internal user. then A will receive an NDR after two days , that 10.10.10.10 is down, ( if the smart host is configured to send the NDR). I hope I understood your query

Sorry to confuse you. Lets make it straight fwd. Internal user A has a FWD set to B(Outside). Now if X sends email to A & if B is not available. Who will receive NDR X or A or both. Hope you understand my query. Ask for any more confusion.

If forwarding is done by the server then the original sender email address is preserved in the envelope header mail from: so the original sender will get the NDR only.James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com