Improve 'send-mail-function' defcustom.

* lisp/mail/sendmail.el (send-mail-function): Provide better
:doc for the available values.

(cherry picked from commit 6f3067324aa83c0e6a44193c81a443d2c98e43d8)

diff --git a/lisp/mail/sendmail.el b/lisp/mail/sendmail.el
index 27d1fdb29602ab67cb7cc39facea6eab725e6469..d258f6f62e4c6e143ae0e1d28c22a0adf9149267 100644 (file)
--- a/lisp/mail/sendmail.el
+++ b/lisp/mail/sendmail.el
@@ -151,12 +151,12 @@ not a valid RFC 822 (or later) header or continuation line,
 that matches the variable `mail-header-separator'.
 This is used by the default mail-sending commands.  See also
 `message-send-mail-function' for use with the Message package."
-  :type '(radio (function-item sendmail-send-it)
-                (function-item sendmail-query-once)
+  :type '(radio (function-item :doc "Use the Sendmail package." sendmail-send-it)
+                (function-item :doc "Query once for which function to use (and remember it)." sendmail-query-once)
                 (function-item :doc "Use SMTPmail package." smtpmail-send-it)
-                (function-item feedmail-send-it)
-                (function-item mailclient-send-it)
-               function)
+                (function-item :doc "Use Feedmail package." feedmail-send-it)
+                (function-item :doc "Use the system mail client." mailclient-send-it)
+                (function :tag "Custom function."))
   :version "24.1")
 
 ;;;###autoload