Doesn't do what one expects Rated 1 out of 5 stars

Doesn't work for me. Selecting a bunch of messages to be rethreaded that some clown had thread-hijacked and then choosing "Rethread" only causes every message to become an immediate reply to the "root" message of the original thread regardless of the cascaded level. i.e., This:

OM
->OML1
->->OML2
->->->HT (OML3)
->->->->HTL1 (OML4)
->->->->->HTL2 (OML5)
->->->->->->HTL3 (OML6)

becomes this after selecting HT, HTL1, HTL2 and HTL3:

OM
->OML1
->->OML2
->HT (OML1)
->HTL1 (OML1)
->HTL2 (OML1)
->HTL3 (OML1)

instead of this:

OM
->OML1
->->OML2
HT
->HTL1
->->HTL2
->->->HTL3

as one would expect. (OM = Orig Msg; OMLx = Orig Msg Level x; HT = Hijacking Topic; HTLx = Hijacking Topic Level x). If only this could be fixed, this would be the greatest add-on since sliced bread.

Some tipps Rated 3 out of 5 stars

I haven't tried this extension yet, at the moment I'm using Header Tools Lite https://addons.mozilla.org/thunderbird/addon/header-tools-lite/ to set the References-header manually.
In the description of that extension I found this:
Some IMAP servers, such as Gmail, do not accept changes if some basic headers (date, sender, the message id, object) are not modified . With the option “Forcing changes with IMAP accounts enabled“, the changes are forced by changing the date of the message of 1 second.

For me it is not working. Rated 3 out of 5 stars

Sounds great. But it is not working for me.

When I am selecting few messages and pickup option "rethread" last selected email is duplicated and nothing more.

Anybody else with similar issue?

Rated 5 out of 5 stars

Extra points for multiselect ;)

For mouse/keyboard dnd, perhaps TotalMessage may be of interest. Original references are stored and a backup is made to Trash if desired.