Yahoo blames Microsoft implementation for Windows Phone 7 data charges

Yahoo has spoken out after being blamed for excessive data charges experienced by some Microsoft Windows Phone 7 (WP7) users.

Microsoft fingered an inefficiency in the synchronisation of e-mail between its Windows Phone Mail client and Yahoo Mail as the cause of rogue WP7 data charges.

In a statement, Yahoo defended its Yahoo! Mail client and said the application is successfully used on millions of mobile phones, including Apple iOS, Google Android, Nokia Symbian and Research in Motion (RIM).

"The issue on the Windows phones is specific to how Microsoft chose to implement IMAP for Yahoo Mail and does not affect Yahoo Mail on these other mobile devices," said Yahoo.

The company added that it has offered Microsoft a near-term fix for its chosen implementation and said it is encouraging Microsoft to change to a standard way of integrating with Yahoo Mail, which would result in a permanent fix.

Microsoft previously blamed an unnamed "third-party solution" for unidentified data use charges on WP7 devices until blogger and programmer Rafael Rivera identified Yahoo as the culprit of the data leak.

Some WP7 users were wrongly charged for up to 50MB a day for checking e-mail and social networking sites.