Google has notified us that approximately 5,000 M+Google Mail accounts might have been affected by a recent issue in Mail that caused some actions taken while viewing a message (e.g. deleting it, marking it as spam, or moving it to a folder) to be inadvertently applied to a different message. The issue occurred between January 15 and January 21.
This issue affected only actions taken in Mail for iOS, Mail in a mobile browser, and Mail Offline. It did NOT affect Mail in a web browser or Mail for Android. This issue is now fixed. However, affected users must take action to re-file these messages in Mail by February 14, 2014.
The M+Google Team has received a list of affected users from Google and is contacting them directly with additional information and instructions. (Those affected might also receive a notification from Google in their Mail application regarding this issue.)
Below is the explanation from the Google Apps Team regarding the cause of the issue:
About the issueThe cause of the issue was a bug in a software update to Gmail on January 15. Once the issue was reported to the Gmail engineering team, they identified the root cause and issued a fix on January 21, and identified the users whose messages may have been incorrectly placed in Trash or Spam folders. The Gmail engineering team performed an internal review and is implementing a series of measures to address the source of the issue, improve early detection of these types of problems, and help prevent recurrence.
We sincerely apologize for the disruption to your organization. Google is committed to continually and quickly improving our technology and operations to ensure secure access and avoid service disruptions.