I have my GMail account setup with Mail.app using IMAP. I accidentally deleted my Sent Mail through Mail.app, emptied the Trash. This propagated to the cloud, and I lost all my Sent items.
The one smart thing I was doing was backing up. So I have the Mail.app backups. I reverted to a backup which had my Sent Mail and started Mail.app back up. Upon restart, my Sent Mail was back, but then disappeared on first sync, because it looks like it pulls email statuses from GMail down to Mail.app, where as I need to push an entire folder/label/mailbox to GMail.
So to sum it all up: How do I sync with GMail using Mail.app so that my local email is pushed to the cloud?