7.6 Spam Suppression Features
As spam and phishing problems become more and more pervasive, sendmail has
added more features specifically targeting those problems:
??? Th eFEATURE(badmx) (?§7.6.1 on page 291) rejects any client hostname, the
domain part of which resolves to a bad MX record (V8.14 and later).
??? Th eFEATURE(block_bad_helo) (?§7.6.2 on page 292) rejects clients who provide a
HELO/EHLO argument which is either unqualified (lacks a domain part) or one of
the server??™s names (V8.14 and later).
* If you have not already done so, you will also first need to declare the FEATURE(access_db).
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7.6 Spam Suppression Features | 291
??? Th eFEATURE(greet_pause) (?§7.6.3 on page 293) suppresses slamming attempts
(V8.13 and later).
??? The experimental FEATURE(mtamark) (?§7.6.4 on page 295) implements the MTA
mark proposal (V8.13 and later).
??? Th eFEATURE(require_rdns) (?§7.6.5 on page 296) rejects clients whose IP address
cannot be properly resolved (V8.14 and later).
??? Th eFEATURE(use_client_ptr) (?§7.6.6 on page 297) causes the connecting client??™s
IP address to be screened early even if the FEATURE(delay_checks) is used
(V8.13 and later).
7.6.1 FEATURE(badmx)??”V8.14 and Later
Most Windows PCs that exist on the Internet lack a fixed IP address.
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