No longer requires both body and subject. One of them is enough.

src/compose.php

@@ -258,18 +258,14 @@
           error message, show=true **/
       global $body, $send_to, $subject, $color;
 
-      if ($body == "") {
+      if ($body == "" && $subject == "") {
          if ($show)
-            plain_error_message(_("You have not entered a message body."), $color);
+            plain_error_message(_("You have not entered a message body or a subject."), $color);
          return false;
       } else if ($send_to == "") {
          if ($show)
             plain_error_message(_("You have not filled in the \"To:\" field."), $color);
          return false;
-      } else if ($subject == "") {
-         if ($show)
-            plain_error_message(_("You have not entered a subject."), $color);
-         return false;
       }
       return true;
    } // function checkInput()