Sorry for the late reply. I've just compiled a new version of my modified email app using the latest CyanogenMod 10.2 source. Works pretty good on my Sony Xperia Z.
Yesterday I took the time and looked at the code of the email app again and I think I found a much cleaner and simpler solution with less code changes. On my Xperia Z it works very good so far. I've attached the code changes and the install zip to this message. Please report any problems that occur with this version. If there are no problems with this version I will try to submit the changes to the CyanogenMod repository. I think this solution could be clean enough for them to merge it into their sources.
For those who have problems installing the zip file: Please check if the email apk file under /system/app is also named Email2.apk. If it has another name then rename the file in the zip file to match the name on your device so that it will be overwritten on install.
I dont know what to do, after installing the latest of your version the exchange keeps the phone awake all the time. Done a clen install of everything but the issue remains. Using it with Exchange 2013.
I don't think that my changes are causing this problem because I didn't change anything in the exchange synchronisation. (This is a completeley separated app) But I also had these problem with the exchange synchronisation before. One time these problems occured because my exchange password was exired and one time I had to completeley delete my exchange account and add it again to solve the problem. Can you try if readding the exchange account solves your problem? (If this does not help try to delete the app data from the E-Mail and Exchange app completely and then readd the exchange account)