|Description||Immediately Reject Undeliverable Email:
ISPs should configure their gateway mail servers to immediately reject undeliverable email, rather than accepting it and generating non-delivery notices (NDNs) later, in order to avoid sending NDNs to forged addresses.
|Industry Role(s)||Service Provider|
|Keyword(s)||Cyber Security;Intrusion Detection;Network Design;|
|Reference/Comments||By rejecting undeliverable email, the gateway mail will inform the sending mail server, which can apply local policy regarding whether or not to notify the message sender of the non-delivery of the original message.
See the following document for more information:
Note that the Best Practices in this grouping are primarily aimed at ISPs that provide service to consumer end-users on residential broadband networks, but may be applicable to other users and networks as well.