# Bounce 5.3.0 Unable ... \[delivered; 5.3.0\]

Attempts to send a Zivver message may result in a non-delivery report (NDR), also called a bounce message. The bounce message appears as follows:

_5.3.0 Unable to specify specific reason due to missing diagnostic code\[delivered; 5.3.0\]_

As the bounce indicates, the message is successfully delivered, but the sender still receives a bounce.

For the error _Bounce 5.0.0_, refer to [Bounce 5.0.0 Unable … diagnostic code](https://docs.zivver.com/en/admin/general/troubleshooting/troubleshoot-ndr.html).

## Cause

The receiving mail server returns an incorrect Delivery Status Notification (DSN). While only a few providers request Success DSNs, Zivver uses them to confirm successful message delivery.

The message shows that it was delivered, but a status 5.3.0 is returned. This indicates that authentication is required.

**Diagnose**

Send a test message to the affected domain using a setup that requests a Success DSN.

**Solution**

Contact the receiving party about the issue so that they can resolve it on their end.

Updated on 2025-08-21