Hi there I'm having a problem and I don't know where to start looking. A couple of users have complained that they are getting outgoing mail bounced back to them and incoming mail bouncing back to the people who sent it. The e-mail addresses being used are the right ones. I'm quite sure the problem is on our end because the users who have complained are random, and it's all happened around the same time. We are running Exchange 5.5 on an NT 4 Server. I know there are many different things that could be causing this, but I was hoping I could get some suggestions as to where I can start looking when this type of thing happens. Thanks in advance Neile -- Neile Bermudes Network Support Tel~ 020 74321241 Mobile~ 07754417478 E-mail~ neile.bermudes@xxxxxxxxx