New antispam features in Sendmail 8.14.0 and above

I have not paid attention to some new important antispam features offered by Sendmail in version 8.14.0 or above. They are :

FEATURE(`require_rdns')

This is to reject messages from SMTP clients whose IP address does not have proper reverse DNS.

FEATURE(`block_bad_helo')

This is to reject messages from SMTP clients which provide a HELO/EHLO argument which is either unqualified, or is one of our own names (i.e., the server name instead of the client name).

FEATURE(`badmx')

The function is to reject envelope sender addresses (MAIL) whose domain part resolves to a "bad" MX record.

I recommend all network administrators who manage Sendmail must enable these antispam functions.