diff --git a/app/Mail/Forms/SubmissionConfirmationMail.php b/app/Mail/Forms/SubmissionConfirmationMail.php
index 3dd3dfe5a..6532e949d 100644
--- a/app/Mail/Forms/SubmissionConfirmationMail.php
+++ b/app/Mail/Forms/SubmissionConfirmationMail.php
@@ -45,7 +45,7 @@ public function build()
                 'fields' => $formatter->getFieldsWithValue(),
                 'form' => $form,
                 'noBranding' => $form->no_branding,
-                'submission_id' => $this->event->data['submission_id'] ? Hashids::encode($this->event->data['submission_id']) : null
+                'submission_id' => (isset($this->event->data['submission_id']) && $this->event->data['submission_id']) ? Hashids::encode($this->event->data['submission_id']) : null
             ]);
     }