The backup I created by passing a configuration file is twice as large as the one I created interactively; it contains all mail directories twice:
- the folders of my IMAP accounts (there are 2 of them) are contained both in root and in the ImapMail directory
- same for the "Local Folders" and "Feeds" directories, which are present both in root and in the Mail directory
(MozBackup 1.4.10, Windows 7)
configuration file (nothing particularly interesting in it, I suppose)