JayMMueller is right on the money.
Further, CSound ignores the fact that Apple can be incredibly insular, to the point that internal departments seem impervious to outside information from customers or the customer facing support team, until they are roundly embarassed in public. Even then, they tend to drag heels.
I still love Apple products, but the above, along with serious questions these repeatedly unfixed issues have to lead one to ask about the quality of Apple QA, give me real pause. Exchange support has been seriously broken since Mountain Lion. I reported and escalated what I saw of these issues within a few weeks of its release. Eventually, even going the letter to Tim Cook route, when support seemed clueless and ineffective, then being routed to an executive support person to help me with my concerns. Still, here we are over a year and many point releases later, with a defective product that Apple still claims 'supports Exchange'.
It doesn't. Maybe it will soon. But without violating NDA, let me say that I am not hopeful. Heck at this stage, they haven't even seemed to lick the issue of Mail wanting to download tons of mail messages and attachments it should already have cached, each time it's instantiated. Exchange servers are fickle. But that points to some serious engineering flaws in Mail.
I'll keep writing bug reports. No one seems to be reading them though.