I can't answer the original question, but I may have a work-around. After hearing "you got message" (MightyROM) one two many times at 3am, I discovered an email schedule program called, appropriately, EmailScheduler. You can find it here:
http://gudensoft.com/?p=236 and on XDA:
http://forum.xda-developers.com/showthread.php?t=438970 . There also a couple of threads around here on it.
The author has stopped development in lieu of
nuevasync.com, but it's worked for me on my TP for almost a year. It lets you choose a start time and an end time. Then you choose how often your email gets checked at those times. I set it for 15 minutes during the day and "manually" at night.