Exchange 2013/2016 - Blocking recipients that are not listed in the global address book

I have the following enabled:

"When the RecipientValidationEnabled parameter is set to $true, the Recipient Filter agent blocks messages addressed to recipients that don't exist in the organization."

RecipientValidationEnabled

I purposely sent a test email to a non-existent email address for the domain and I got a NDR back saying that the email address doesn't exist.

Should I be getting a NDR back or should I not be getting a NDR back and what exactly doesRecipientValidationEnabled do?

Thanks