quite honestly I would suggest you save the whole profile, not just bits of it. makes restoring much easier.

Windowskwy + R type %appdata% in the windows explorer copy the thunderbird folder and it's sub folders to a usb drive. on the new machine or reinstalled device reverse the process (again using %appdata% to gtet the location for the root of your application data)

It is a much larger backup and does include a lot of redundant information especially if you use the windows search (thousands of wdseml files for windows search integration) but has the benefit of an immediate restore exactly as it was before without the muss and fuss of trying to import things one bit at a time and dealing with the vagarities of CSV files.

The copy replacing the old profile into the new install can even be done prior to installing Thunderbird so the first run "just works" instead of creating an empty profile that requires work.

Note if you have changed the paths in account setting to locations outside the profile, this simplified copy will not work as it does not include data in the modified locations. But then neither did your approach.

I'm quite happy to copy the whole directory to my backup drive, and then reverse the process later, but I don't see how you're recommending I do this. What is the significance of "%appdata%", etc.? Should I just copy the folder called 'Mozilla Thunderbird', which is in the 'Program Files (x86)' folder, and should I copy it back to there in the new installation? Bob Eccles

%appdata% takes you directly to the folders that contain your data for Thunderbird. Copy the folder named Thunderbird that you find there to your backup device and later back to the corresponding location on your newly rebuilt computer.

What you are talking about with Program Files is the executable, the program itself, and frankly, you're better off installing that afresh from a download rather than trying to move an installed program from one Windows installation to another. Even though Thunderbird doesn't use the registry itself, Windows will set up shortcuts and register Thunderbird as a mail application. You miss out on all that if you don't go through the formal install process.

You do not need to "export" or "import" anything. Just copy the profile.

https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data

%appdata% is a windows environment variable that resolves to the current users location of the application data folder. Actually the appdata\roaming folder as opposed to the local etc application data folders. Because of it's nature you do not have to know what version of windows (documents and settings on XP resolves), what the user name that forms part of the path is. Nor do you have to have hidden files and folders feature turned on so you can find the hidden appdatafolder in windows file manager.

From a support perspective is takes about 10 steps out of the instructions getting someone to the place you want them to be in appdata. See the instructions for enabling hidden files and folder as a partial example. https://support.microsoft.com/en-au/help/14201/windows-show-hidden-files

You can get mode information on the windows environment variable here https://technet.microsoft.com/en-us/library/cc749104(v=ws.10).aspx

I tell you to copy the Thunderbird folder as it contains a single file that points Thunderbird to your actual profile. that location, by default is a sub folder of the %appdata%\Thunderbird folder and all data it stored below that root Thunderbird folder. It is only when people try and move things by changing the default location of their profile or the location shown in account settings for folders that this simplified method does not work. So unless you have changed default locations, copying %appdata%\Thunderbird will get you everything.

Copying the program files is futile. All your settings (including add-ons) and data are stored in the profile folder normally a sub folder of %appdata%\Thunderbird. So are better of reinstalling Thunderbird after you copy, that way windows is happy with the installation and the few registry updates that are required like setting the default email client are done.

>>quite honestly I would suggest you save the whole profile<< Does this backup the address-book also?

Yes, the profile includes all your Thunderbird address books. You may find this article informative: http://kb.mozillazine.org/Profile_folder_-_Thunderbird#Files_and_folders_in_the_profile That gives you some indication of how much else is preserved by copying the profile; account settings, filters, address books, stored passwords, extensions, customizations etc etc.

I also need to bakup my Firefox. I realise that Firefox is not part of Thunderbird, and is not covered on this forum, but is it true that I just need to copy the Mozilla folder (which contains the Firefox profile) in just the same way? I want to be able to restore my bookmark menus, etc.

BobEccles said

I also need to bakup my Firefox. I realise that Firefox is not part of Thunderbird, and is not covered on this forum, but is it true that I just need to copy the Mozilla folder (which contains the Firefox profile) in just the same way? I want to be able to restore my bookmark menus, etc.

That would be correct, as far as my knowledge of Firefox goes. They are very similar under the hood.

Note that a browser profile is typically a load of bookmarks, your extensions and your stored passwords. It is much smaller than an email client's profile.

Note there are various online sync options for your browser, which work well with its smaller profile.