I have been having issues with my Droid off and on since our Exchange 2010 upgrade, and the upgrade of Android from 2.1 to 2.2. The best solution I have found is shaftys023′s modified email.apk file. Seems to work on both stock 2.2 Droid phones and rooted Droid phones.
Here are instructions for installing it…
Download shaftys023 modified email.apk file here.
You will have to register at the forum to download it (its free and fast). I didn’t want to host it/steal it
On your DROID, pull down the menu at top and “select to copy files to/from your computer.” (hook your phone up to PC)
Copy over the downloaded email.apk file to a directory on your phone.
Install ASTRO manager (file manager). This is free in the marketplace, just search ASTRO.
Launch ASTRO, browse to your email.apk file, click on it, select “app manager” and then click “upgrade.” (this will overwrite your current email.apk)
Setup your exchange 2010 account and enjoy!
Launch ASTRO manager