Review for AutoarchiveReloaded by Marty
Rated 5 out of 5 stars
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".
To create your own collections, you must have a Mozilla Add-ons account.