Windows 2000 server running exchange 5.5
Clients running windows xp pro and outlook 2000
I have a few users who keep getting undeliverable email messages. The message says that the address that they are sending it to is not a valid email address. The problem lies in the fact that these users did not send the original email and I am puzzled as to what to do to verify that we are not hacked. I have relay disabled.
Where else to look?