Exchange Server Email Drains Battery Life iPhone

I have been having battery draining issues for months on my iPhone 3Gs. Sunday, my second visit to the Genius Bar resulted in getting a new replacement 3GS phone. I still noticed a significant battery drain issue (lose about 20% battery every hour) with this new phone. hmmm - cant be hardware, I thought. Ill check out some software solutions to the battery draining fast.
After much more experimenting I have FINALLY determined that my work email account is the problem. I did all the normal suggestions of PUSH off, Location OFF, screen brightness low, Notificatons OFF, etc. Those things MIGHT have made a slight difference (I couldnt tell if they did), but when I switch my work email account to INACTIVE that does the trick. I have four email accounts, and the work account is the only one that uses MS EXCHANGE Server. It also doesnt seem to matter (much?) if I have it on PUSH or FETCH. It also has not helped to delete then reload the account to the phone (or a new phone restored from the previous for that matter).
There is another person at my work that has a 3GS on the same server (MIS verified that it IS on the same hardware), and he does not have the battery drain issue.
I need suggestions - PLEASE!
-Jeff
iPhone 3Gs iOS 4