diff --git a/src/mailer.js b/src/mailer.js
index d0713363a..9efa25889 100644
--- a/src/mailer.js
+++ b/src/mailer.js
@@ -61,7 +61,7 @@ async function sendMail(mailOptions) {
         }
     }));
 
-    const transportSendMail = util.promisify(transport.sendMail).bind(transport);
+    const transportSendMail = util.promisify(transport.sendMail.bind(transport));
     const [error] = await safe(transportSendMail(mailOptions));
     if (error) throw new BoxError(BoxError.EXTERNAL_ERROR, error);
     debug(`Email "${mailOptions.subject}" sent to ${mailOptions.to}`);