Adds an optional log_dns_record configuration key (default 0) to the - #182
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pacellig wants to merge 1 commit into
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Adds an optional log_dns_record configuration key (default 0) to the#182pacellig wants to merge 1 commit into
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SPF, DKIM and DMARC handlers. When enabled, each handler performs one
additional DNS TXT lookup after the authentication check and appends the
raw record content as a comment node to the Authentication-Results entry:
Authentication-Results: mail.example.com;
spf=softfail smtp.mailfrom=sender@example.com
(x-dns-record=v=spf1 redirect=_spf.google.com);
dmarc=fail policy.applied-disposition=none header.from=example.com
(x-dns-record=v=DMARC1; p=reject; rua=mailto:dmarc@example.com)
Comment nodes are permitted by RFC 8601 and are ignored by
standards-compliant downstream parsers and mail clients.
When investigating authentication failures it is useful to see the actual
DNS policy that drove the decision without having to perform a manual DNS
lookup. This is particularly valuable in automated processing pipelines
where the raw record is needed alongside the authentication result.
- The DNS lookup uses the handler's existing get_object('resolver')
mechanism, so it respects any mock resolver configured in tests.
- Failures (NXDOMAIN, timeout, resolver error) are caught with eval
and forwarded to handle_exception — they never affect the
authentication result or cause the milter to tempfail.
- The option defaults to 0 so there is no behaviour change for existing
deployments.
- One extra DNS round-trip per enabled handler per message when the
option is on.
| File | Change |
|---|---|
| lib/Mail/Milter/Authentication/Handler/SPF.pm | log_dns_record option: default_config, lookup block, pod docs |
| lib/Mail/Milter/Authentication/Handler/DKIM.pm | Same |
| lib/Mail/Milter/Authentication/Handler/DMARC.pm | Same |
| share/authentication_milter.json | Add "log_dns_record": 0 to SPF, DKIM, DMARC sections |
| t/04-unit-handler-log-dns-record.t | New — 6 subtests (3 handlers × enabled/disabled) |
pacellig
marked this pull request as ready for review
August 4, 2026 10:51
Author
|
@notbrokenjemma would appreciate a review when you have a moment, thanks! |
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SPF, DKIM and DMARC handlers. When enabled, each handler performs one additional DNS TXT lookup after the authentication check and appends the raw record content as a comment node to the Authentication-Results entry:
Comment nodes are permitted by RFC 8601 and are ignored by standards-compliant downstream parsers and mail clients.
When investigating authentication failures it is useful to see the actual DNS policy that drove the decision without having to perform a manual DNS lookup. This is particularly valuable in automated processing pipelines where the raw record is needed alongside the authentication result.