I am experiencing the very same issue. I use to be able to check my hotmail and yahoo mail from my wireless pocketPC but I now can only check my Yahoo mail using the messaging option. I would love to know what I need to do to resolve this issue as well.
PocketPC OS is made by Microsoft, and I'm pretty sure there must be a way for it to retrieve email from hotmail.com. When I setup my Message (came with my rx3115), it only had the option of pop and IMAI (I think). I tried both, it didn't work when I tried to retrieve my mail. Anyone have an idea how I could set this up?