I have exchange 5.5 on winnt4.0. I can receive and send email almost to everybody. I am trying to send email to a specific domain(exchange 2K) but all emails are in queue and showing that Host unreachable. The other doamin has windows 2000 with exchange 2000. They also can receive and send email to everybody.Exchange 2000 can send email to exchange 5.5 but 5.5 can not send to exchange 2000. Does anyone has any clue? Thanks in advance Rakesh jain