Does anyone tweak the DKIM scores given by SA? There are plenty of
scenarios where DKIM has failed, yet SA does not give the email a
particularly high spam mark. 3 example test cases below. I guess I was
expecting SA would score DKIM failures more aggressively if there are
problems with the signing:
Case 1. Actively modify "from" field of the message and send in manually via
SMTP keeping the same signature.
X-Spam-Status: No, score=-1.379 tagged_above=-10 required=6.6
tests=[ALL_TRUSTED=-1, BAYES_05=-0.5, DKIM_SIGNED=0.1,
NO_DNS_FOR_FROM=0.001, T_DKIM_INVALID=0.01,
T_HEADER_FROM_DIFFERENT_DOMAINS=0.01, T_NOT_A_PERSON=-0.01,
T_UNKNOWN_ORIGIN=0.01] autolearn=no
Authentication-Results: zqa-398.eng.vmware.com (amavisd-new);
dkim=fail (1024-bit key) reason="fail (message has been altered)"
header.d=dkimtest.com
Case 2. Update signature on a domain, but don't update it in DNS.
X-Spam-Status: No, score=-0.057 tagged_above=-10 required=6.6
tests=[ALL_TRUSTED=-1, BAYES_20=-0.001, DKIM_SIGNED=0.1,
NO_DNS_FOR_FROM=0.001, RDNS_NONE=0.793, T_BIG_HEADERS_2K=0.01,
T_DKIM_INVALID=0.01, T_HELO_NO_DOMAIN=0.01,
T_LONG_HEADER_LINE_80=0.01, T_NOT_A_PERSON=-0.01,
T_THREAD_INDEX_BAD=0.01, T_UNKNOWN_ORIGIN=0.01] autolearn=no
Authentication-Results: zqa-398.eng.vmware.com (amavisd-new);
dkim=fail (1024-bit key) reason="fail (bad RSA signature)"
header.d=dkimtest.com
Case 3. Don't populate DNS record with DKIM signature at all
X-Spam-Status: No, score=-1.957 tagged_above=-10 required=6.6
tests=[ALL_TRUSTED=-1, BAYES_00=-1.9, DKIM_SIGNED=0.1,
RDNS_NONE=0.793, T_BIG_HEADERS_2K=0.01, T_DKIM_INVALID=0.01,
T_HELO_NO_DOMAIN=0.01, T_LONG_HEADER_LINE_80=0.01,
T_NOT_A_PERSON=-0.01, T_THREAD_INDEX_BAD=0.01,
T_UNKNOWN_ORIGIN=0.01]
autolearn=no
Authentication-Results: zqa-398.eng.vmware.com (amavisd-new); dkim=neutral
reason="invalid (public key: not available)" header.d=dkimtest.com
Thanks,
Quanah
--
Quanah Gibson-Mount
Sr. Member of Technical Staff
Zimbra, Inc
A Division of VMware, Inc.
--------------------
Zimbra :: the leader in open source messaging and collaboration
