From the way you tell it this seems more like a Palm question than a MS Office question. Possibly it's an Exchange Server question, or a Windows Server question, but I doubt it.
Just a thought for a possible workaround: let him move all his old mail from the Exchange folder that is synchronised to an archive folder.
Here is the situation. My boss has a Tungsten T2. in addition he likes to add all the toys that he can find. (ie: Wireless access, Camera add on, mail readers, e-book readers, and a list to long for this space.) He has lost the ability to hot sync and up load his mail from our mail server. we are running W2000 Server and exchange 2000. When it does hot sync he gets a lot of very old mail and all of his entries in the date book are listed on the current day(all 7200, almost 3 years worth).
If you have any ideas or comments they are greatly appreciated. Thanx