diff --git a/proxy/mailing/mail.php b/proxy/mailing/mail.php
index 87d342f..1da8121 100644
--- a/proxy/mailing/mail.php
+++ b/proxy/mailing/mail.php
@@ -17,7 +17,7 @@ if (!$target_mail_view) civiproxy_http_error("Feature disabled", 405);
 civiproxy_security_check('mail-view');
 
 // basic restraints
-$valid_parameters = array(  'id'   => 'int'  );
+$valid_parameters = array(  'id'   => 'int', 'cid' => 'int', 'cs' => 'string'  );
 $parameters = civiproxy_get_parameters($valid_parameters);
 
 // check if id specified