Q If I buy a new computer, is there a way I can transfer Thunderbird's Junk Filter 'intelligence' by copying some files, rather than it having to re-learn from scratch?
A The junk filter data is in a file called training.dat. This in contained in the randomly named directory in ~/.mozilla-thunderbird. Thunderbird keeps the name of the directory in ~/.mozilla-thunderbird/profiles.ini. Why do you want to transfer only the junk mail filters and not the rest of your data? Even if you use IMAP and keep all your mail on the server, there are still configuration files and filter controls that you would want to keep. Otherwise you will have to recreate or reconfigure everything. You only have to transfer the .mozilla-thunderbird directory to your new computer to carry on where you left off. If the two computers are networked, you can do this with scp
scp -pr user@oldcomputer:.mozilla-thunderbird ~
Otherwise use sneakernet, with something like a USB flash drive, to transfer the files. In this case, you should tar the directory to preserve the file attributes. Copying directly to a FAT filesystem as used on most flash drives, will remove file ownerships and permissions.
# on old computer tar czf /media/usbdrive/thunderbird.tar.gz .mozilla-thunderbird #on new computer tar xf /media/usbdrive/thunderbird.tar.gz
Whichever method you use, do this before you run Thunderbird on the new system, otherwise it will create a .mozilla-thunderbird directory with new settings. Even if you are using the same user name on both systems, it is quite possible that the new distribution may be allocating a different numeric ID to the user. You can fix this by running this in a root terminal
chown -R myuser: ~myuser/.mozilla-thunderbird