I recently set up TimeMachine with a 750 external hard drive, but it's been filling up very quickly. Even though I only have a 150GB primary drive (mid-2009 13" MBP), It's managed to fill up 350 GBs in the last couple days. I also noticed that each time it backs up, most likely once a day (I leave the drive disconnected most of the time), it seems to do about 14 GBs each time. I rarely change files, except for Mail App, which I use with Gmail (IMAP). I also have quite a few photographs, but doesn't Time Machine only backup what has been changed? Should I not have it backup Mail?