Try this site: https://connect.mozilla.org/

There are add-ons for multiple signatures:

https://addons.thunderbird.net/en-US/thunderbird/addon/signature-switch/

https://addons.thunderbird.net/en-US/thunderbird/addon/quicktext/

Thanks for these but I've burnt my fingers on addons that are not listed as working with my version, currently 110.0beta Would much rather it was a feature of the app and not an add-on which will crash as releases progress. But thanks for the pointers.

This is a Wish List item but I can't locate where to place it ;-)

https://connect.mozilla.org/ The link is also on the Thunderbird help menu under "feedback".

On the basis that I have Folders for Companies and Individuals based on their email addresses, I require different signatures for each Folder. This was a feature in the Virtual Access email software, where when a folder was the 'active' or highlighted folder, you used the 'Signature' icon or menu option, whereby you created the 'Signature' for that particular folder. So for my friends my signature was 'All best, Jonathon' or for my family 'Love, Dad' or 'Love, Jonathon' for acquaintances or companies, a signature that included my address and contact numbers.

But I am guessing if you use the signature switch addon your needs will be met. https://addons.thunderbird.net/en-US/thunderbird/addon/signature-switch/?src=ss

Wonder why I only got to see the question until I replied. Oh well.

Now. You are beta testing and want addons to work with it. Not realistically going to reliably happen. That is about when many addon authors start making updates and testing to see if their addon still works in the new version. I suggest you use a release version for production work and a beta version for testing.