Interesting sicne this is what the Yahoo! help says.
The ability to access Yahoo! Mail using an email reader program such as Outlook, Eudora, or Thunderbird is only available to customers of our premium Yahoo! Mail Plus service.
Have you checked to see if the incoming server address has changed?
yahoo really is a pain... but JimH is talking about accessing Yahoo mail on the computer you do have to pay for Y+ and the secret is that Yahoo Free will allow ymail to be fetched on an iPhone. There is no cost to do that.
Are you attempting to download your mail over 3G? Switch to wifi to attempt to fetch your mail.
Yahoo may be testing an IP address location saftey net and may block mail requests outside of your home state...
At&t has it's primary datacenter in Kansas if I'm not mistaken. So if you live in colorado, yahoo may block until it has a colorado IP to access the system...
It may sound off-the-wall but I have seen this happen a few times before...
It fails with both wifi and 3G, I live in Illinois.
I checked my Yahoo acount - just the simple free one, not Mail Plus, and I didn't see anything relevant in any of the Options.
I also restored the iPhone software, that didn't change anything either.
I've never had Yahoo Mail Plus, and all has been working fine for 5 years, I've been on the iPhone 4 since last Summer - one never needed Mail Plus for the iPhone before, and I think they would've listed it necessary with in iPhone when they listed Eudora, Thunderbird, etc. That's not the issue.
Whatever happeneded, happened sometime Friday afternoon, there was no unusual behavior from me that day, I can access the email received before that, and it does see that there are new messages to download, and it does try to download: it will flash "Downloading 1 of 13 Messages" with the status bar, like it would normally, but as soon as you see that, it dispears and goes back to the status quo.
I sent a mesage to Yahoo, looking forward to their reply.
It just stopped working and has trouble downloading new messages... I see now
Log-in to your yahoo webmail, move/remove/delete the new messages. If you put your email into folders, do so and then see if those messages are in the proper folders on your iPhone.
Some things to change/edit to force the iPhone to display more mail-
Iphone settings > Mail, Contacts, Calendars >
Show 100 Recent Messages
turn off "Organize by Thread"
Fetch new Data > Push
Also, if yahoo continues to fail/frustrate, use trueswitch to move to a new email provider-
Some interesting results playing with email folders:
Within yahoo webmail I moved an email that was displaying in both webmail&iphone Inboxes and moved it to a folder. This change then updated as it should on the iPhone.
But, then, when I moved the message back to the Inbox in webmail, the message rightfully disappeared from the folder in the iPhone, but was NOT able to go back to the Inbox on the iPhone - I could tell by quick downloading status in the iPhone email account that it was trying to "download" it, but could not. When I went back to webmail and moved the email back to the folder from the Webmail Inbox, it was then updated and back in the folder in the iPhone. In othe words, the auxially storage folders seem to work fine, it's just the iPhone Yahoo Inbox that is not taking in new message.
So the issues seems to specifically relate to the Inbox folder on the yahoo email in the iPhone. The Inbox seems to be blocking all incoming new mail, whether a new message coming in, or a transfer move from a folder.
I went through my iPhone settings, just changing things back and forth, but nothing effecting the downloading.
I hope this sparks new thoughts, at least I have a more detailed case for Yahoo - I appreciate the suggestion, thank you!
POP no longer works with the free version of Yahoo mail, you need to upgrade to the paid version. The other option is to download the free Yahoo mail ap... seems to work well. Take a look at this link http://help.yahoo.com/kb/index?page=content&y=PROD_MAIL_MOBILE&locale=en_US&id=S LN3422&impressions=true