Our exhange server cannot connect to our ISP's SMTP server.
I enter the smarthost address - go to advanced - outbound security and enter the username and password.
I have tested with outlook and it connects and sends ok but not with the exchange virtual server.
I prefer connecting directly with DNS but quite a few of our contacts companies refuse the connection with the error:
'Mail rejected because your IP is in DUL' which I understand to be a blacklisted problem.