I tried reverting but It won't let me have my profile and I have to recreate it. That's very sad. Anyone has a solution for that feature I'm looking for?

When I said version 114, I meant 102.

There is a reading pane, which I think you are referring to as a preview pane. but to the best of my knowledge it has never treated email any different that when mail is read in a tab or a window. SO this double click to mark as read leaves my a little lost. As I would have an inbox full of unread mail as I have never used the window or tab option to read mail.

I see someone else asking the same question on reddit this week and getting a very similar response https://pay.reddit.com/r/Thunderbird/comments/17er69r/mark_messages_as_read_but_only_when_they_are/

I understand there was such an option in Eudora back in the day, but I never heard of it in Thunderbird.

Wow! That was a super-quick answer for a free-software. And it's not even a back-handed compliment, you are actually quicker than paid ones! Yes, my request is confusing. It's just that in version 102, nothing could mark a message as read. Only a double-click to open an email. I know it's slower and counter productive but I was used to this way. Right now, I realize that I am getting used to not having that feature at all.

Still, if someone have an answer, I would be happy.

Also, what I really wanted to have is the extension Mailbox Alert compatible with version 115 but this is for another department.

Thank you very much!

Still, you guys did a terrific job with version 115.