diff --git i/src/PrivateMsgService.php w/src/PrivateMsgService.php
index 1ce03f4..002974a 100644
--- i/src/PrivateMsgService.php
+++ w/src/PrivateMsgService.php
@@ -439,7 +439,9 @@ class PrivateMsgService {
         '%thread_id' => $thread_id,
       ]);
       $recipient = $this->entityTypeManager->getStorage('user')->load($recipient_id);
-      $this->mailManager->mail('privatemsg', 'privatemsg_mail', $recipient->getEmail(), 'ru', $params);
+      if (!empty($recipient->getEmail())) {
+        $this->mailManager->mail('privatemsg', 'privatemsg_mail', $recipient->getEmail(), 'ru', $params);
+      }
     }
   }