The Site has a stand alone Exchange Server 2003. They cannot access Web mail externally over a period of about 2 months. The Site has a Watchguard firewall with port forwarding open on 443 to the Exchange IP address. After numerous tests externally I decided to access OWA on the LAN. Hey Presto! no access. So I have excluded the Firewall as the fault. I've only worked on Exchange over the past year and have no idea were to start looking in the System manager, can anyone suggest a diagnostic approach? I.e Were to start looking?