If you use Message Storage Type "maildir" (one file per message), it makes incremental backup easier. Furthermore, your profile, which stores all your email, contacts, add-ons, etc, is very easy to relocate to another PC.
Very versatile two-pane, multi-tabbed file manager.
Folder comparison, calculate folder size,
Most file operations could be queued so I do not have to wait for completion.
Portable version allows you to add this to your toolkit across PC.