The scenario: I get messages from clients and co-workers written in ALL CAPS, which is sometimes very annoying (I'm "old school" and netiquette means "shouting").
The idea: I would like that directly in Thunderbird there is the possibility (simple and basic) to change the capitalization of the selected text when writing and/or replying to messages. Nowadays, any text and code editor offers this function (even spreadsheet programs).
Currently there are few options among the extensions for Thunderbird, but either they don't work or they are paid and require an Internet connection (or a user account) and it is something that seems to me to a certain extent, unnecessary (to say the least).
Thank you very much for the consideration.