Hi info1465, Mozilla and Firefox are not email clients.

Which extension did you used to use ?

Maybe we can contact the creator or find an alternative.

Hi Robert We used the add on 'editmailsubject' in Thunderbird. But that add on now says it's not compatible with our Thunderbird, which I think is because Thunderbird has been updated. And I'm sorry, I'm not very good with computers & don't understand what you mean when you say Mozilla & Firefox are not e.mail clients. Is there another add on we could use? All old versions aren't compatible either so not sure what we can do. Thanks for your help so far anyway

Hi again info1465, What I meant is that Firefox is not an email app like Thunderbird.

Did you mean to post your question next door on the Thunderbird Forum ?

If you did, that's OK. Maybe a moderator will move your question over there.

n the meantime, I'll take a look around to see if I can help you find something.

Try this link:

https://addons.thunderbird.net/en-US/thunderbird/search/?q=editmailsubject&appver=&platform=

This looks promising:

Mail Merge https://addons.thunderbird.net/en-US/thunderbird/addon/mail-merge/?src=search

and it is compatible with the latest version of Thunderbird.