I don’t know if you got into this problem or not yet, but YOU WILL! :-D. I had this problem one day and I was unable to setup any mobile device to connect to my Exchange Server ActiveSync setup…
I got this problem and it took me one day to find out what is going on…
The problem is you configure ActiveSync on the Exchange server and you put the certificate on the server and on the firewall (TMG or ISA) then when somebody with a mobile device tries to connect using ActiveSync, he fails, and cannot get to the server, even if you check about the problem you will find everything on Exchange and ISA or TMG is clear and no dust on it!
Well, the problem maybe not in the Exchange or the firewall, there is a big chance that you can solve it from the Active Directory!… Read the rest “Fixing the problem when users cannot connect to exchange server using ActiveSync to sync their data”