thunderbird: how to backup mailbox and restore quickly

["Yuwen Dai" <yuwend@gmail.com>]

Dear all,

I'd like to backup part of my Inbox, e.g., the emails of last year as my Inbox becomes larger and larger. I also want to restore and read the backup quick in thunderbird if need.  What's your suggestion?

I once backuped the whole inbox on a CD-ROM, and set the "local directory" on the mount point of CD-ROM, failed. It seems the directories must be writable.

I also tried to create another `local folders' account, failed too.  Thunderbird doesn't permit doing that.

Best regards,
Dai Yuwen