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.

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.