Last week a bunch of Gmail users were affected by a glitch. The issue lasted from January 15 to January 21 for some users. Google acknowledged the issue and set about fixing it. The service was repaired, but Google has now sent out an email to some affected users telling them more about what happened.
The mail says that between January 15 and January 21 an issue in Gmail cause some actions like deleting, reporting spam, starring, archiving, or moving to a folder to be applied incorrectly to a different message than what the user was looking at. That means that emails people sent out could have ended up in spam folders or the trash on the receiving end accidentally.
The email sent to some people has a list of users whose messages were sent to trash or spam folders accidentally. Google says that affected users need to advise recipients that they need to check spam or trash folders for messages. The messages can be resorted now by moving them back to the inbox.
The catch is that all of the messages sent to the trash or spam folders need to be re-filed by February 14. Messages are permanently deleted 30 days after they end up in the trash folder. The email also notes that the cause of the Gmail issue was a bug in a software update. Google had identified the cause and fixed the issue by January 21.