diff --git a/src/Util/Filter/StringFilter.php b/src/Util/Filter/StringFilter.php
index f1c3592..433c0e1 100644
--- a/src/Util/Filter/StringFilter.php
+++ b/src/Util/Filter/StringFilter.php
@@ -467,7 +467,7 @@ public static function filterEmailCommon(
         }
 
         // if validate DNS
-        if ($validateDNSSR === true && !@checkdnsrr($explode[0])) {
+        if ($validateDNSSR === true && !@checkdnsrr($explode[1])) {
             return false;
         }