Hi amprince48, Firefox has settings for which mail program or site to use, for example, locally installed Thunderbird, the Gmail website, etc. Ref. Change the program used to open email links.

However, I don't think Firefox has any way to tell the email program/site what account to use -- Firefox is only sending a few data points, such as the To address, or Subject line and body text. Is it possible there is a default account setting in your email software or webmail site that might help with that part?

If it helps, my email program is Thunderbird.

Are you saying that Firefox does open Thunderbird when you "click on an email address in Firefox", but that Thunderbird tries to send an email to the wrong email account?

If that is the case, the setting you need to fix is in Thunderbird, not in Firefox. I can't help with Thunderbird support as I have have never used Thunderbird, I have been using "web mail" exclusively for the last 15 years or so.

If you want, I or another Moderator here can move this question thread over to the Thunderbird question queue, but I don't know how long I'll be here. OR you can ask another question in the Thunderbird area.

https://support.mozilla.org/en-US/ over there, but select Thunderbird in the lower-right corner of Pick your product area on that page. Firefox for Windows, Mac, & Linux desktop / laptop computers is the first entry at the upper-left corner of that page.

moved this thread to the Thunderbird support queue

I have three email addresses in Thunderbird - a personal one, a newsletters one and an old one that still occasionally receives significant emails but was supposed to be terminated over a year ago. When I click on an email link in Firefox, it defaults to the old one as the email I am sending from.

In Thunderbird, go to Tools > Account Settings, select the account that you wish to send from by default, then click the Account Actions button and select Set as Default