Latest in the continued investigaton of the mysterious Windows Phone 7 phantom data usage, Rafael Rivera discovered Yahoo's IMAP server is the root cause of the issue. He reports:
Yahoo's IMAP server (winmo.imap.mail.yahoo.com) doesn't respond to FETCH requests correctly.
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.)
Although the communications aren't sending large chunks of data, times the number of emails you currently have in your Yahoo account, and you can easily rack up the extra few megabytes per sync.
Microsoft has confirmed and also includes information about another, semi-unrelated issue for some reason:
We've determined that an inefficiency exists in the synchronization of email between the WP 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'll be rolled out in the coming weeks.
- In the meantime, customers can mitigate this issue by following these steps:
- On the Start screen of WP7, click on the arrow at the top right
- Choose "Settings" from the app list
- Choose "email & accounts"
- Choose "Yahoo! Mail"
- Click on the setting under "Download new content"
- Select a less frequent setting. If you are using the default setting (every 2 hours), change this setting to "manually"
- Click on the setting under "Download email from"
- Select a shorter time range. If you're using the default setting (the last 2 weeks), change this setting to "the last 7 days"
Microsoft has also identified an issue with our Exchange ActiveSync [EAS] email synchronization protocol that may affect a very small percentage of users
- This issue can be caused by email that exceeds the mail server email size setting or is sent to an invalid email address
- This issue can potentially affect email services that utilize the EAS protocol -- Outlook and Gmail for example
- The immediate mitigation is for users to delete mail that appears "stuck" in the outbox
- This is currently scheduled to be fixed in a near-term end user update from Microsoft
[tags]winp7,wp7,phone mail,mobile mail,imap,eas[/tags]