The original post: /r/linux by /u/buovjaga on 2024-12-18 10:45:36.

We were looking into a supposed LibreOffice bug, which turned out to be something else entirely. It seems there is a huge number of Linux systems where the handler of mailto URL schemes is set to Firefox. This breaks xdg-email from making the right kind of call when relaying an attachment from an application to an email client. Maybe someone can enlighten me as to who is ultimately responsible, Firefox/Thunderbird or how they are packaged?

You can check the current state on your system with

xdg-settings get default-url-scheme-handler mailto

On my Arch Linux, I could correct the handler with

xdg-settings set default-url-scheme-handler mailto org.mozilla.Thunderbird.desktop

I found the name of the .desktop file from the file list in https://archlinux.org/packages/extra/x86_64/thunderbird/

This was the only way to correct it in my case. Any kind of override in a mimeapps.list file was futile.

If someone has an idea on how to correct this with Snap or Flatpak packages, let me know.