It is longer term issue.
when i click some e-mail on a webpage in Firefox (mailto: link) nothing happens.
I have checked and in Firefox about:preferences#general is mailto set to Thunderbird.
I have tried to set Always Ask instead, but no prompt. Not restarted FF after this change.
Thunderbird is running.
Private window also no action.
Other browser opens TB new message dialog.
When i search for default, and open Default apps, TB is set as default.
As mentioned, this is long term issue, i have logged in like yesterday, when i execute “mailto:mail@example.com” in a new FF tab, it does nothing. Neither Private window or FF Troubleshooting mode. Other browser handle mailto: OK.
grep -rl 'mailto:' ~
.firefox and .mozilla folders does not seem to contain any matching conf file
Thank You all. Issue solved. You were right, this was Firefox misconfiguration. I apologize i have not checked about:config
Indeed i had it set to false (unsure why) which is non default state.