khalidzubair wrote:
It's only with my gmail accounts. All of them are IMAP. No filters no recent changes either. Had the same settings for years and nothing of the sort ever happened.
When troubleshooting, everything is suspect until verified, and effectively nothing can be assumed. (If I've had the same settings for twenty years and the behavior of the configuration changed, I'd still verify all the settings.) OS X doesn't know from an Archive folder, unless there's a rule added for it within Mail.app. GMail has an archive label, and can be configured to move via Gmail filters. If you're at your storage limit quota, GMail might well delete stuff, too.