Hotmail and yahoo do not support Push on Android.
I have been using K-9 for over a year now and have tried to configure it in all possible ways, but Push only works with Gmail.
Thanks for your help guys, but I'm also experiencing problems getting my gmail to push to my phone. Under my Inbox on gmail it says "sync 4 days". Does this mean it syncs every 4 days? can't see to figure out a way to change that setting...ideas? thanks