I'm not buying this
Compare the number of users reporting the issue against the number of users using Yahoo! mail...
Unless of course the issue is for ALL IMAP accounts...
(Yes, I'm the other WP7 user)
Microsoft's own Mail app and Yahoo! Mail have been implicated by the software giant as the cause of the Windows Phone 7 bug that has caused some handsets to rack up users' data transfer tallies. Microsoft last night blamed an "inefficiency" in the way its Windows Phone Mail app talks to Yahoo! Mail. The result: "larger than …
People will only be reporting the issue if...
1) They use Yahoo mail
2) They use IMAP to access Yahoo mail
3) They have high volumes of emails
4) They are checking their data usage
5) They actually notice their usage has gone up a lot
6) They sync with Yahoo often
7) They back-sync more than a couple of days
So, quite a narrow section of the WP7 using fraternity then.
And yes I'm another WP7 user, but I'm using Hotmail so no problems from my end.
If Yahoo are not implementing the IMAP protocol correctly, and it certainly sounds like they aren't, then it's definitely not Microsoft's fault. Although you would have thought that MS would have discovered the fault in pre-production tests, and that they would have released this info a lot sooner to those affected and presumably paying excesses on their data plans.