Yahoo for Windows Phone 7 proven to cause excessive data usage(update)



yahoo-logoWe still do not have a definitive cause for the “phantom data” problem on a small minority of Windows phone 7 handsets, but Rafael Rivera has been another to point a finger at Yahoo for at least part of it, and he has proof.

He managed to intercept packets traveling between his smartphone and the yahoo servers dedicated to Windows phones, and discovered the connection uses 25 times more data than it should.

He writes:

What I discovered was shocking, although not surprising. Yahoo’s IMAP server ( does not respond to FETCH requests correctly.

Now, that may not look like much but sandwich the extra bytes with encryption and multiply the size of each chunk by the number of emails in your inbox (or folder)... yeah. Scary.Yahoo is sending ~25 times as much data as it needs to. (This can also be read as: Your phone is downloading ~25 times as much data as it normally would, had you sided with another email provider.)

He suggests as a solution either disable 3G access for mail (Settings –> Cellular –> Data roaming options) or set their yahoo account to download new content only (Yahoo Mail –> Settings –> Sync Settings).


Paul Thurrot is confirming that Microsoft has formally acknowledged that Yahoo Mail was indeed the culprit. From the blog

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.

Read the rest of the blog for instructions on how to mitigate the issue. Microsoft has also identified another issue   with their Exchange ActiveSync (EAS) email synchronization that may affect a small number of users. The blog has the temporary fix, as well as a statement from Microsoft promising a fix in a “near-term end user update.

Read more detail at here.


Thanks Chad for the tip. Brianna for the update.

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}