Hotmail and Yahoo mail are often have problems with email clients other than their own app. This is the way MS and Yahoo want it. My wife had the best success with Hotmail using Maildroid. K9 usually works, but can be inconsistent in our experience. My solution was to not use Hotmail! I still use my Yahoo mail account, but have given up on using any second party apps to access it and use the official app instead. One caveat with Maildroid. We found out just about the time we replaced the wife's Epic 4G that it was responsible for a lot of the issues we had with that phone (weird lock ups/slowdowns, black screens with clicking noises).