This is the only response that i got from t-mo:
T-Mobile Blackberry users are experiencing issues with receiving email to Yahoo accounts, and are also unable to configure Yahoo email accounts for use with Blackberry devices. Therefore, RIM still needs more examples of Yahoo email issues to investigate and fix this issue quickly. |
If you are able to connect to the Internet and view your other emails, please contact us over the phone so that we can transfer you to RIM directly to fix your issue.
but everything started working 2 days after it started. Who knows.