Exchange on SBS2003 wont allow connection other than OWA

All,

Following a forced rebuild of my SBS2003 server, the exchange part of the server refuses to play. The symptoms are that email is coming in and going out correctly, but users can only access exchange via OWA. Mobile devices (Windows Mobile and Android) refuses to connect, and outlook clients refuse to connect.

I suspect (but I may be wrong) that this may be down to the fact that OWA refuses to use form based authentication ? it insists on showing a pop-up login screen for authentication. When i try to connect a mobile device (tried both Android and WM), the users are marked as mobile users, there permissions allow mobile access.

It should allow form based authentication ? Under Exchange > Servers > Protocols > HTTP> Exchange Virtual Server I have ?enabled Forms Based Authentication? ticked, compression High set.

Under IIS settings, I have my server > Web Sites> Default Web Site > Directory security set with the certificate (which is picked up ok for OWA), and under Authentication and access Control, the settings are:

Enable anonymous access is ticked (with the user name and password as per the default), and both Integrated Windows Authentication and Basic Authentication ticked. The default domain is set to Dogsbodysystems.local as described below.

As far as the Outlook connection goes ? no user can validate their settings. Regardless of whether they go through the outlook setup of mail, or use the control panel MAIL snap in, when they go to validate, the message produced is ?The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete?.

Does anybody have any idea what I can try, what is going on, or why outlook/mobile devices refuse to connect?!?


Technical Details:
Server is running SBS2003 SP2, with exchange 2003 SP2 ? exchange has been reinstalled just in case, and SP2 reapplied
Server is running IIS and ISA 6.0, with external certification in place.
Outlook clients are both 2003 and 2007
My computer is named : DOGBODYSYSTEMS
Exchange is named (via the exchange server management) : DOGSBODY
Domain is named : Dogsbodysystems.local
External web address is : www.dogsbodysystems.co.uk
(note in the above, ?dogsbody? replaces my company name)