Earlier I wrote here too. As Mountain Lion comes. Re: Exchange under Mountain Lion
I change my exchange hoster four times:
Most of the problems I have had with my Exchange hosting www.df.eu (Exchange 2007 on Windows 2003 R2 server),
then I had www.cortado.com (Exchange 2007 on Windows 2008 R2 server) and
then I was at www.qualityhosting.de (Exchange 2010 on Windows 2008 R2 server).
Now I am on microsoftonline.com and most of problems are not more.
But:
1. Definitly 10.8x have problems with Exchange, there are no problems with iOS and also no problems with Outlook in Windows.
2. Apple support said to me that these forum is for users. Normaly they don't search here written bugs.
3. They also said to me you have to call Apple support. Good if you have Apple Care! And you should get second level support because mostly the first level don't know so much for exchange and they say to call Exhange support of Apple (company or business support or like this) which is very expensive. Don't do that and be sure to get second level.
4. But since 2009 I have my first Apple with Leopard. Snow Leopard, Lion, Mountain Lion and some new MacBook Pro. I am since 1983 on IT-Branche with Microsoft till 2009. Mail of 10.8.x ist buggy, buggy, buggy!!!
CALL Apple support. Only this way may be bring a solution.
I don't want to change to Windows (only under Prallels I have VM) because all other things are superior on OS X (never be slow like 6 months after windows installation, changing to a new hardware without new installation of all programs, ...)