Thank you, Olivier. I am happy to see that it works out of the box in 20.04 focal LTS. The fix was released a month ago, but since I anyway had custom association configured in ~/.config/mimeapps.list, I forgot to check it earlier.
-- You received this bug notification because you are a member of Desktop Packages, which is subscribed to thunderbird in Ubuntu. https://bugs.launchpad.net/bugs/1960614 Title: Add mid: scheme handler to thunderbird.desktop Status in thunderbird package in Ubuntu: Fix Released Bug description: Since thunderbird-91 version (actually even earlier, but only ESR releases are packaged in Ubuntu) it is possible to open particular messages from command line using Message-ID: thunderbird mid:a...@example.com See e.g. https://bugzilla.mozilla.org/264270 However to open links from other application "mid:" scheme should be advertised in the thunderbird.desktop file: MimeType=x-scheme-handler/mailto;application/x-xpinstall;x-scheme- handler/mid; Please, adjust this field in the desktop file. To check that the change has effect the following command may be used: xdg-open mid:a...@example.com Notice that it is not upstream issue. Thunderbird developers left desktop integration up to maintainers of Linux distributions. Long time ago it was possible to create such links to particular messages using thunderlink extension but migration from XUL to WebExtension add-ons broke it. Support of mid: scheme restores linking of mail messages from other applications. There is a related issue: request to add message/rfc822 MIME type in lp:1861262 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/1960614/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp