diff --git a/plugins/bc-mail/src/View/Helper/MailformHelper.php b/plugins/bc-mail/src/View/Helper/MailformHelper.php
index 5fbfa8408a..cd1e81f76a 100755
--- a/plugins/bc-mail/src/View/Helper/MailformHelper.php
+++ b/plugins/bc-mail/src/View/Helper/MailformHelper.php
@@ -296,6 +296,8 @@ public function authCaptcha(string $fieldName, array $options = [])
      */
     public function getGroupValidErrors(ResultSetInterface $mailFields, string $groupValid, array $options = [], bool $distinct = true)
     {
+        // 呼び出し元のイテレーションに影響が出ないようにクローンを作成
+        $mailFields = clone $mailFields;
         $errors = [];
         foreach ($mailFields as $mailField) {
             if ($mailField->group_valid !== $groupValid) continue;