IMHO I hate yahoo mail, gmail is the only way to go - its kinda like having a Lamborghini in the garage but driving a Yugo around if you use yahoo when gmail is so much better lol - I mean you can use yahoo that's your choice but why would you want to ? Lol
I have the same problem , started 4 days ago. i have done 6 hard resets, deleted and re-installed yahoo 4 times, and did a complete restore to new twice. none of which helped. so i called apple and they tried to say it was a software issue and wanted to charge me $30 or $70 for the apple care. in order to fix the problem. finally i got hold of another apple person who agreed it might be hardware related and advised i send in my phone or go to the nearest apple store (120 miles away). So i went to the VZW corporate store and told the lady what has happened and what i did to try to resolve this issue. She gave me a certified as new replacement, which will be here tuesday. But according to VZW as of friday 1-13-2012 they have had no complaints of this issue. but after reading this post i may cancel the new phone and try to find a work around. has anyone tried the microsoft exchange route using yahoo. i know it will work with gmail as my fiance had to do that in order to get her gmail to work.
I think its a Yahoo issue. I had the same problem for a few weeks back in 2010 when I first got an iPhone that was linked to some kinda Yahoo server problem. It worked itself out after a few weeks. Really isn't that big of a deal, because lets face it, if you can't press the "Mail" icon every so often, you might be too lazy! Lol
I believe the problem is Yahoo. I can't access the email options from my PC either. All my other accounts work fine, and the problem is happening on both my iPad2's, my iPhone4, and iPod touch. Too bad switching email addresses is such a pain!
It's definitely a yahoo issue and I wanted to give my update since a lot more people wrote here:
I thought it might even be a jjailbreak issue so I did a new restore of my phone and deleted and added the account again, nothing. I tested it out by sending emails to both yahoo and gmail and the gmail notification would come through but yahoo wouldn't.
I finally went ahead and imported all 3000+ emails through the gmail feature and changed my yahoo to forward all emails to gmail. The emails are the same besides the domain change, so now when I reply from gmail I doubt people would even notice.
I did lose my folder structure since gmail only imports from inbox, but oh well, it's been a good run in the last decade but now with push technology I expect that service and if someone doesn't deliver I will go to someone that does.