/usr/share/applications/mutt.desktop is in mutt 1.5.21-5ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 | [Desktop Entry]
Categories=Office;Network;Email
Comment=Simple text-based Mail User Agent
Exec=mutt
Icon=mutt
Name=mutt
MimeType=x-scheme-handler/mailto
NoDisplay=true
Terminal=true
Type=Application
|