Yahoo blames Microsoft for Windows Phone 7 data bug

Microsoft's implementation of email retrieval settings on Windows Phone 7 is to blame for Yahoo Mail customers using unexpectedly large amounts of data on that smartphone platform, Yahoo has said.

In the latest twist to the search for culpability over the issue — some users have been consuming 25 times the data that should be needed to retrieve Yahoo Mail emails on Windows Phone 7 handsets — Yahoo said on Wednesday that Microsoft was responsible. A day before, Yahoo had itself apologised for "any inconvenience this is causing to users".

"Yahoo Mail is widely available on tens of millions of mobile phones, including those running on Apple iOS, Android, Nokia Symbian, and RIM," Yahoo said in its latest statement. "The issue on the Windows phones is specific to how Microsoft chose to implement IMAP for Yahoo Mail and does not impact Yahoo Mail on these other mobile devices. Yahoo has offered to provide Microsoft a near-term solution for the implementation they chose, and is encouraging Microsoft to change to a standard way of integrating with Yahoo Mail, which would result in a permanent fix."

ZDNet UK has asked Yahoo to clarify whether it meant Microsoft had accidentally established IMAP settings for Yahoo Mail that resulted in the bloated data usage, or whether it was implying a deliberate move on Microsoft's part, but the company had not responded at the time of writing. Similarly, Microsoft has not commented on Yahoo's statement.