fix(email): do not pass auth object to transport if no auth data present

re #312

server/lib/notifications/agents/email.ts

@@ -29,10 +29,13 @@ class EmailAgent implements NotificationAgent {
       host: emailSettings.smtpHost,
       port: emailSettings.smtpPort,
       secure: emailSettings.secure,
-      auth: {
+      auth:
+        emailSettings.authUser && emailSettings.authPass
+          ? {
               user: emailSettings.authUser,
               pass: emailSettings.authPass,
-      },
+            }
+          : undefined,
     });
   }