Apparently the emacsclient-mail.desktop file doesn't conform to the
Desktop Entry Specification at
https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#exec-variables
which says about the Exec key:
| Field codes must not be used inside a quoted argument, the result of
| field code expansion inside a quoted argument is undefined.
However, the %u field code is used inside a quoted argument of the
Exec key in both the [Desktop Entry] and [Desktop Action new-window]
sections.
* etc/emacsclient-mail.desktop (Exec): The Desktop Entry
Specification does not allow field codes like %u inside a quoted
argument. Work around it by passing %u as first parameter ($1)
to the shell wrapper.
* etc/emacsclient.desktop (Exec): Use `sh` rather than `placeholder`
as the command name of the shell wrapper. (Bug#60204)
This is necessary to get the Gnome desktop to show “Emacs (Client)”
when the user searches for “emacsclient”.
* etc/emacsclient.desktop, emacsclient-mail.desktop (Keywords): Add
“emacsclient”.
These are intended for use as mailto: URL handlers, not for launching
directly, so we can reduce clutter by hiding them from a desktop
environment’s menus.
* etc/emacs-mail.desktop, etc/emacsclient-mail.desktop: NoDisplay=true
We provide both an emacs.desktop and an emacsclient.desktop, so for
consistency let’s do the same with mail.
* etc/emacs-mail.desktop: Extract suggestions for using emacsclient
from comments to create emacsclient-mail.desktop.
* etc/emacsclient-mail.desktop: Send mail using an existing Emacs
rather than starting a new one.
