I have an Exchange 2003 with OWA running. Users can access it easily from most places. There is one location, from which our users cannot access OWA. They have internet access and can open webpages in general but not my OWA.
I suspect they are blocking some ports in their network firewall configuration, and I would like to ask their IT guys, but I don't know which ports are required for OWA or what port(s) they might be blocking.