Microsoft has identified Yahoo Mail as the culprit behind the mysterious data usage reported by scores of Windows Phone 7 owners. The “phantom data” issue was first brought to light earlier in the year when users began noticing that they were burning through their monthly data allowances at unusually high rates. On January 20, Microsoft issued a vague statement addressing the problem:”we have determined that a third-party solution commonly accessed from Windows Phones is configured in a manner that potentially causes larger than expected data downloads.”
Over two weeks later, we now know that the “third-party solution” responsible for quietly gorging on users’ data is Yahoo’s free mail service, Yahoo Mail. “We have determined that an inefficiency exists in the synchronisation of e-mail between the Windows Phone mail client and Yahoo Mail,” Microsoft said in a statement released on Monday. “This inefficiency can result in larger than expected data usage for a very small percentage of users.” Microsoft also said that a fix will be coming in a matter of weeks.
Microsoft’s confirmation comes after programmer and blogger Rafael Rivera announced that he had discovered Yahoo Mail to be responsible for hogging data. Rivera looked at IMAP packets sent to and from Windows Phone 7 and discovered inconsistencies with Yahoo’s IMAP server when it was being asked to fetch new messages. Instead of sending back a very small amount of data, Rivera said that Yahoo was sending data that was about 25 times larger than it should have been. “Your phone is downloading ~25 times as much data as it normally would, had you sided with another email provider,” Rivera said in a blog post.
Shortly after Rivera’s blog post was published, Microsoft responded for requests for comment by issuing a statement confirming Rivera’s finding and providing instructions on how to avoid the glitch:
We have determined that an inefficiency exists in the synchronization of email between the Windows Phone Mail client and Yahoo! Mail.
This inefficiency can result in larger than expected data usage for a very small percentage of users.
• Microsoft and Yahoo! have worked together to identify a fix, which will be rolled out in the coming weeks.
• In the meantime, customers can mitigate this issue by following these steps:
1. On the Start screen of Windows Phone 7, click on the arrow at the top right
2. Choose “Settings” from the app list
3. Choose “email & accounts”
4. Choose “Yahoo! Mail”
5. Click on the setting under “Download new content”
6. Select a less frequent setting. If you are using the default setting (every 2 hours), change this setting to ‘manually’
7. Click on the setting under “Download email from”
8. Select a shorter time range. If you are using the default setting (the last 2 weeks), change this setting to ‘the last 7 days’
It’s not yet clear exactly when Microsoft might have been aware of Yahoo Mail’s role in the “phantom data,” but it seems more than likely that it knew well in advance of yesterday’s official acknowledgment. “I realize I’m just stating the obvious, but there’s no reason, and no excuse, for this information to not have been provided earlier,” author and blogger Paul Thurrott said in a posting.
Microsoft’s Windows Phone 7 launched in October of 2010. Yahoo has yet to address its role in the data issue.