+(defcustom notmuch-command "notmuch"
+ "Name of the notmuch binary.
+
+This can be a relative or absolute path to the notmuch binary.
+If this is a relative path, it will be searched for in all of the
+directories given in `exec-path' (which is, by default, based on
+$PATH)."
+ :type 'string
+ :group 'notmuch-external)
+