I had all sorts of problem getting ActiveSync for exchange set up and working. I found Sembee's very helpful article here: http://www.amset.info/exchange/mobile-85010014.asp
I followed it, and it worked a treat - thank you very much Sembee :)
However, the one thing I can't do, having run through all the instructions, is that I cannot turn encryption back on on the newly created virtual directory, mentioned in the article as "exchange-oma", and keep things working. All the other Exchange related folders have encryption turned on. If I turn the encryption back on on the "exchange-oma" folder though, ActiveSync stops working. Turn it back off, and everything is happy straight away.
Is it important to have on, or is the encryption on the other folders enough to guarantee encryption across all access? Also, what exactly is in / linked to the "exchange-oma" folder? As it was created from meta data gathered from the original "exchange" virtual directory, and registry key was added, does it not contain content that needs encrypting?
Sorry to waffle, I look forward to any input.