further refinement..

lang/en_utf8/moodle.php

@@ -897,7 +897,7 @@
 $string['maxsize'] = 'Max size: $a';
 $string['memberincourse'] = 'People in the course';
 $string['messagebody'] = 'Message body';
-$string['messagedselectedusers'] = 'Select users have been messaged and the recipient list has been reset.';
+$string['messagedselectedusers'] = 'Selected users have been messaged and the recipient list has been reset.';
 $string['messagedselectedusersfailed'] = 'Something went wrong while messaging selected users.  Some may have received the email.';
 $string['messageselect'] = 'Select this user as an email recipient';
 $string['messageselectadd'] = 'Add / send message';