I've been using FreeFileSync and like it, but Thunderbird email syncs take forever. The problem is Thunderbird doesn't use folders but compressed files to store its data. In my TB profile there's no Inbox folder where emails are stored, no Sent folder, etc. There are only files named Inbox or Sent. When FreeFileSync does a sync it copies the whole file every time instead of just the new data. I'd like to find a sync program that can do incremental syncs at a file level. PDF-XChange Editor can do this on PDF files so I know it's possible. I found some programs that say they can do incremental, but don't get specific enough and I'm still not sure they can do what I want. Would anyone know first-hand of any programs that can do it? Free or commercial is fine.