Popular email software “Thunderbird”. Some people were surprised that the error “SSL certificate cannot be verified” suddenly started appearing in Sylpheed 3.7, and like me, I replaced it by referring to the initial setting method of Thunderbird and the migration method from Sylpheed. Isn’t it not a few?

After a while, the announcement of the release of Windows 11 emerged. It’s autumn 2021. Therefore, many people may be thinking of replacing the PC with a new one instead of upgrading the OS.

The problem is data migration of “Thunderbird”. Especially those who have registered and used a lot of accounts should be depressed and unavoidable. So, although it is a PC between Windows 10, I would like to introduce an easy method that I actually migrated.

Bulk backup method of “Thunderbird”

This was described in detail in the following reference article.

Reference: Thunderbird backup method (Windows 10)

First, open some folder-part ① in the figure (the figure is an example of the Explorer icon, but you can also use the Windows icon → Documents, or open any folder anyway).

Delete the part of the address bar (② in the figure), paste the following, and press the Enter key.

%APPDATA%/Thunderbird/Profiles

Then the following screen will appear.

As shown in the figure above, there should be two folders, “○○ .default-release” and “△△ .default”.

Of these, “△△ .default” (red frame) is the file that contains all the account settings, folder information, and email information.

If you copy the whole thing somewhere, the backup is completed.

… It’s too easy to be surprised.

If you receive an e-mail after that, the content will change, so be sure to do it just before the migration, and then do not start the e-mail software on the old PC (if you do not want to use it completely anymore, the previous “△△ .default” If you move it instead of copying it, you won’t make a mistake, but let’s leave it somewhere until the migration is complete.)

How to restore backup

After installing Thunderbird on your new computer, quit it and open the folder using the same procedure as for backup.

Then, a folder called “○○ .default-release” and a folder called “XX.default” (names other than △△ .default) should be created.

After confirming, rename the “△△ .default” folder you backed up to “XX.default”.

Replace the changed folder with the automatically created “XX.default”.

When you’re done, start thunderbird.

If you can restore the email account and data you used so far, you’re done (I was able to migrate this way).

If “XX.default” does not exist, please paste “△△ .default” as it is.