So, if someone with an @hotmail.com account sends you an email and you pick it up on your PocketPC then it is empty? That's quite unusual. Which is probably why no one can help you. No one here has ever experienced that before. You could try email support at PocketPC.com or at hotmail.com and see what they have to say.
It could be a format of email that hotmail is sending, like how most emails are in pure text or HTML. Maybe hotmail uses some java commands WITHIN their emails to "track" usage and external POP accounts. PocketPCs don't like java

. But that would only prevent viewing if that was the INTENTION of the script. Maybe hotmail only allows your Outlook client to receive mail from your account in order to "secure" it, (but we all know it's to limit our personal online freedom, because Microsoft is the devil, of course).
I'm just throwing things up into the air. But it would have to be SOMETHING with the actual information with in hotmail emails. Open up the source to the hotmail emails using Outlook on your desktop and look for anything suspicious that could be the culprit. I doubt that there is a fix that you could implement, but you could give hotmail and microsoft a big heads-up.