Mozilla Connect

When I use Firefox or WaterFox and click on a MAILTO link,  I get an error saying that Thunderbird profile is missing.  Thunderbird is set in Windows 11 for this type.  Is there something I can change in Firefox/Watefox?

I have been using MOZBackup for very long time to back up Firefox and Thunderbird profiles.  Mozbackup make it very easy to restore settings, etc.  when needed.  I have been trying out Waterfox to privacy concerns and noticed that Mozbackup doesn't r...