With recent reports revealing that tech blogger Rafael Rivera had discovered that Yahoo was the unnamed `third-party' which caused the `phantom data' issue for Microsoft's Windows Phone 7 (WP7) users, Yahoo Tuesday apologized for the problem centering round the company's Web mail service.

After Rivera's packet sniffing probe found that Yahoo was sending back unusually massive amounts of data every time the WP7 handset users checked for new mail, Microsoft has also acknowledged that Yahoo was indeed the third-party - which Microsoft had thus far refrained from naming - responsible for the `phantom data' problem that was reported in mid-January.

Apologizing for the inconvenience caused, Yahoo said in a statement: "While our default settings on all mobile platforms realize this approach, we have determined that an inefficiency exists in the synchronization of e-mail between Windows Phone Mail clients and Yahoo Mail, which can result in larger than expected data usage for some users."

Further adding that that a fix for the problem was around the corner, and will be released "in the coming weeks," Yahoo said: "Tens of millions of people check their Yahoo Mail from their mobile device each day, and we know they want their mobile mail experience to be fast, rich, and real-time."

However, with Yahoo stopping short of disclosing whether the fix can be made without users needing to update the system software of their handsets, users presently require a dial back whenever mail updates are checked on their WP7 handsets.