Install Thunderbird as a RFC 2392 mid: URL opener
With this, Thunderbird will direclty recognize mid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx@sender.com URLs and make them clickable, allowing cross-email hyperlinks.
dest="$HOME/.local/share/applications/thunderbird-mid-opener.desktop"
mime="x-scheme-handler/mid"
name="$(basename "$dest")"