diff --git a/modules/contrib/rules/src/Plugin/RulesAction/SystemSendEmail.php b/modules/contrib/rules/src/Plugin/RulesAction/SystemSendEmail.php
index f0f6d9b1..b7d2f449 100644
--- a/modules/contrib/rules/src/Plugin/RulesAction/SystemSendEmail.php
+++ b/modules/contrib/rules/src/Plugin/RulesAction/SystemSendEmail.php
@@ -109,7 +109,7 @@ class SystemSendEmail extends RulesActionBase implements ContainerFactoryPluginI
    * @param \Drupal\Core\Language\LanguageInterface|null $language
    *   (optional) Language code.
    */
-  protected function doExecute(array $to, $subject, $message, $reply = NULL, LanguageInterface $language = NULL) {
+  protected function doExecute( $to, $subject, $message, $reply = NULL, LanguageInterface $language = NULL) {
     $langcode = isset($language) ? $language->getId() : LanguageInterface::LANGCODE_SITE_DEFAULT;
     $params = [
       'subject' => $subject,
@@ -117,8 +117,13 @@ class SystemSendEmail extends RulesActionBase implements ContainerFactoryPluginI
     ];
     // Set a unique key for this mail.
     $key = 'rules_action_mail_' . $this->getPluginId();
-
-    $recipients = implode(', ', $to);
+    switch(gettype($to)) {
+      case 'array' :
+        $recipients = implode(', ', $to);
+        break;
+      default :
+        $recipients = $to;
+    }
     $message = $this->mailManager->mail('rules', $key, $recipients, $langcode, $params, $reply);
     if ($message['result']) {
       $this->logger->notice('Successfully sent email to %recipient', ['%recipient' => $recipients]);