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Be careful. Make full backup before archiving !

It works if your email provider archive is compatible with your Thunderbird archive setting.

Interesting is that Thunderbird vanilla archive handles it without issue by ignoring sub-folders but this add-on does not at least in my case.

Things get weird if email provider archive service doesn't support sub-folders and you got enabled "archive by years" or/and "Keep folder structure" in Thunderbird.
In my case it created folder structure in duplicate folder called archive with empty sub-folders but placed all messages into real archive root despite having option "archive by years" or/and "Keep folder structure" activated in Thunderbird settings.

Workaround: set Thunderbird archive to custom folder eg. called "~archive" or turn off "archive by years" and "Keep folder structure".