Some says that Thunderbird history and configuration can lasts 20 years
How help people to backup in a smart way the folder of your favourite mailclient?
(keep @alefattorini away from this topic… he would migrate everything to clientless solutions 
)
The folders should all be server-side in any event–that’s the point of using an IMAP server.
For Thunderbird it’s easy to do at the client side, you only have to copy the profile folder. At Windows for example it is
C:\Users\UserName\AppData\Roaming\Thunderbird\Profiles\yourProfile
The profile name is cryptic.
But you have to close TB before, otherwise it can’t copy all files.
For backup and migration i used many times “MozBackup”, which is not actively deployed. A little advantage: zip compression of the archive.
But with a backlash: no multicore optimization for compressing.
Also, i’m questioning myself if VSS could improve (in Windows enviroment) could ease and speedup the backup.
'cause Maildir version of Thunderbird is still stuck
On a linux laptop or pc you only need to copy the .thunderbird directory in your local profile folder. (most of the times /home/yourname/.thunderbird)
When you install TB on a new linux pc/laptop all you have to do is copy back that .thunderbird directory in the new profile.
It keeps all your plugins and emailaccounts (I have 4 mailaddresses configured in my TB)
MozBackup copied the folder and compressed it. You could write a script to copy and compress it automatically.
MozBackup also can cherry pick interesting things like software and account settings, moreover the extensions.