It may turn out that the “Always On” Direct Push email technology found in the Messaging & Security Feature Pack for Windows Mobile 5.0 may not be “Push” technology at all.  Windows Mobile 5.0 email capabilities are much like those of regular email clients, periodically checking for email on a scheduled basis.  True Push technology, like that found Research in Motions BlackBerry Enterprise Server is completely server based and pushes email to the BlackBerry handheld devices whenever there is new mail message.

This is significant because it takes more power to send a transmission than it does to receive a transmission.  A Windows Mobile 5.0 device that has to check to see if there are new messages on an Exchange Server may be more battery-life challenged as compared to devices that take a true Push approach.