Hi everyone,
Exchange and Apple Mail - the endless story.
We've did some investigation in our company to know what is going on with this crazy problems - most where ontime problems and we never where able reproduce the things.
what we know now are two main things on the way to the solution:
1. configure EWS on the Exchange server. There are limits for timeouts and filesizes defined in the Exchange web.config file. Change the to something reasonable. Howto: http://technet.microsoft.com/en-us/library/hh529949(v=exchg.141).aspx
2. "Apple Support say's ask Microsoft" has to be changed in "ask your firewall administrator" and then "Teach the Apple Mail Developer to learn how to develop software"
Why? as Apple Mail is still not able to use thing like "RPC-over-HTTPS" they use the EWS to contact the Exchange server. This services are normally published thru firewalls to make them secure.
What you can see if you do some research is that there are lots of requests to theese firewalls from Apple Mail Clients while contacting the Exchange system. In normal configurations theere request will drop the connections at one point. if your part of a corporate network whith multiple Apple Mail Clients all theese request are initiated from your corporate network address (NAT) of your gateway. So with even some hands of Apple Mail Clients every normal firewall configuration will start dropping the connections and this will cause some special effects to the Apple Mail endusers :-(
Conclusion
If you are not part of a corporate network (homeoffice, ie.) the EWS web.config change and some firewall changes will make your Apple Mail work.
For cooporate networks the solution we prefer is building an VPN and waiting until Apple is doing their job.
good luck to all,