diff --git a/application/Espo/Core/Mail/Importer.php b/application/Espo/Core/Mail/Importer.php
index da44ce5a57..a2eed69fca 100644
--- a/application/Espo/Core/Mail/Importer.php
+++ b/application/Espo/Core/Mail/Importer.php
@@ -71,7 +71,10 @@ class Importer
 
             $email->set('isBeingImported', true);
 
-            $subject = $message->subject;
+            $subject = '';
+            if (isset($message->subject)) {
+                $subject = $message->subject;
+            }
             if (!empty($subject) && is_string($subject)) {
                 $subject = trim($subject);
             }