OSX 10.8.4 Mail 6.5
About 4 months ago I opened Mail one morning and all of my 800+ emails were gone out of the Inbox. The Sent and Flagged folders were also empty. I carried the iMac in to an Apple retail store Genius Bar and they restored all of my emails from my Time Machine external HD backup but with no other "fixes" or comments on what went wrong. Last week the same thing happened. I restored myself from TM but also scheduled a tech phone call with Apple. The Apple rep had no explanation for why this happens and just ended the call because I had restored my emails myself. Anyone know why this may be happening and a resolution to prevent it from reoccurring?