Rated 4 out of 5 stars

Great - but it seems that I have to choose this every time I view the message. Is there any way to set this persistent, and for a whole folder, not a single message?

No, the setting is forgotten when you switch between messages. The Thunderbird team decided to remove the "per folder" setting, see: https://bugzilla.mozilla.org/show_bug.cgi?id=1671880 (the folder charset was removed in part 2 there). For news, the server default charset is used. If you want to discuss the matter further, contact me via e-mail.

Rated 5 out of 5 stars

Thank you, thank you , thank you!!

This was driving me nuts. I'm danish/swedish, and every mail was completely forked upon sending them. This has absolutely save my sanity :)

Not sure what you mean by "was completely forked". Generally Thunderbird sends everything in UTF-8, so this add-on is only needed in corner cases for "bad" incoming e-mail. You can contact me if you want to discuss this further.

Rated 5 out of 5 stars

Thanks to this addon developer. Shame for TB developers :(

Rated 5 out of 5 stars

Great! I was very upset when saw that one of my newsgroups is not readable after upgrade to TB 91, as messages there were not is UTF-8. This addon allows reading it.
It has two gotchas however.
- It does not work for message list pane (subjects in message list are sill <?>). At least for my KOI8-R encoding.
- It does not remember the selected charset, so when I select a message again, I still need to go to menu and choose the charset. For me, the ideal extension will allow to override a charset for a folder.

This review is for a previous version of the add-on (1.0.3). 

Newsgroups are another kettle of fish, sadly. Usually subjects should be pure ASCII and RFC2047 encoded or raw UTF-8. I know that newsgroups have some funny ideas.

The charset per folder was removed in TB 91, right?

In the account setting for News / Server Settings there is a "Default Text Encoding". Does that help?

Please send me an e-mail with the details of the newsgroup.

Rated 4 out of 5 stars

Glad someone was kind enough to think of the users rather than get rid of functionality willy-nilly.

The extension does what it says, except that the menu item is called "Text Encoding New"; I'd drop the New.

This review is for a previous version of the add-on (1.0.2). 

Yes, the "new" will be dropped in due course. But since this also works in TB 78 where we still have "Text Encoding", the menu entry needed to be different unless I made it conditional.

Why only 4 out of 5 :-(