Clicking mailto: links does nothing, context menu options greyed out
AFAIU programs which use WebKit are responsible of handling mailto:
links, so issue #215923 reported in WebKit's Bugzilla belongs here:
Clicking on a mailto link (the ones at https://www.scottseverance.us/mailto.html for instance) doesn't launch the mailto handler. Tried with the default mailto-handler in Gnome-shell (Thunderbird). The same link correctly launches Thunderbird in both Firefox and Chromium. Tested with Web 3.36.3 in Gnome Shell 3.36.4.
Using Eolie links can be opened and the program configured as default for email (Evolution) opens a composition window just fine.