Why does my Exchange account work on my iPhone, but not Mail.app? I can set up my work Exchange account just fine on my iPhone, but I can't get it to work on Mail.app under Snow Leopard.

I have read some forums and understand that mobile devices use ActiveSync in order to access Exchange mail and I thought Snow Leopard introduced this feature to Mail, but I can't seem to get it working.

I have tried just about every combination of settings I can think of.

My iPhone asks for a domain, but I can't find a similar setting in Mail. I have tried entering my username as domain/username to no avail.

Has anyone had experience/similar problems with this?
Most likely because your corporate exchange server is running Microsoft Exchange Server 2003. Snow Leopard now only connects to Exchange 2007 (See http://www.apple.com/macosx/exchange/) whereas Leopard used to connect to Exchange 2003 using the OWA mechanism.

iPhone supports both Exchange 2003, 2007 and 2010 it seems (See iPhone User Guide , page 2);