iPhone and iPad use a different way of accessing the server.
I don't know the exact details, but we are using Zarafa instead of Exchange and have the same problem:
iPhone and the likes can connect to Zarafas z-push interface, which is some identical interface to the native Exchange interface, while the desktop e-mail application tries to interface with the web front end (via http) of the server.
These are completely different setups and it depends on the actual installation of the server to get this going.
So, you will most likely need different access parameters for the desktop - and the web mail feature has to be enabled on the Exchange server.
In my opinion using the web mail interface is just silly. On the other hand, the native protocol has less features comparedto the web front end, so you are somehow stuck with sins of the past.
Did you ever figure the problem out with MS exchange server and your iMac? I just bought my wife an iMac (our first) and you explained our problem exactly. I've worked with her company's IT department and even went to the Apple store to see if they could help. I'm stuck! If you were able to figure it out and can lend a hand I greatly appreciate it.
Same problem for me. There are three Exchange accounts I can access via my iPhone and iPad but, on my iMac (running Lion):
- one won't connect at all,
- one will connect for receiving, sending and accessing folders but won't let me move messages between folders, and
- one worked fine until this week and is now very intermittent in connecting at all.
The latter is, as far as I know, the latest version of Exchange, the first is an old one due for update later this year and I've no idea what version the other one is.
As I say, all work fine with iPhone and iPad, and via browser (Safari, Firerfox or IE).
Just installed latest Mountain Lion update (10.8.4) and all Exchange accounts accessible through Mail. Contacts and Calendar. The Apple blurb about the latest update mentions fixing an Exchange Calendar issue but not equivalent issues in Mail and Contacts. However, having read that I thought I'd try to see if it had any effect on mail and the previously errant accounts all work fine.