I don't know if my problem is on the iPhone side or Yahoo Mail server side, but I don't always get Yahoo Mail Push on my iPhone Mail App. And yes I set up my iPhone to run Push for everything including Yahoo Mail. My GMail and Hotmail Push however works 100% of the time and happens almost instantly. Note that I dumped the iPhone Mail App default for GMail setting which doesn't support Push and followed web wisdom to set up GMail as Microsoft Exchange for Push to work perfectly all the time. Maybe it's the same thing for iPhone Mail App's Yahoo Mail default setting? However, I can't successfully set up Yahoo Mail as Microsoft Exchange because none of the SMTP server names I tried for Yahoo works. If you know of the problem, know a solution, know the correct Yahoo Mail SMTP server name, or know anything about the matter, I want to hear from you.