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Custom spamassassin rules for bad SPF/DMARC headers

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This commit is contained in:
Jeff Volkenant 2020-10-07 11:29:19 -07:00
parent 3a59fe834f
commit 840f84da1a
1 changed files with 50 additions and 0 deletions
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50
setup/spamassassin.sh
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@ -67,6 +67,56 @@ tools/editconf.py /etc/spamassassin/local.cf -s \
"add_header all Report"=_REPORT_ \
"add_header all Score"=_SCORE_
# Authentication-Results SPF/Dmarc checks
# ---------------------------------------
# OpenDKIM and OpenDMARC are configured to validate and add "Authentication-Results: ..."
# headers by checking the sender's SPF & DMARC policies. Instead of blocking mail that fails
# these checks, we can use these headers to evaluate the mail as spam.
#
# Our custom rules are added to their own file so that an update to the deb package config
# does not remove our changes.
#
# We need to escape period's in $PRIMARY_HOSTNAME since spamassassin config uses regex.
escapedprimaryhostname="${PRIMARY_HOSTNAME//./\\.}"
cat > /etc/spamassassin/miab_spf_dmarc.cf << EOF
# Evaluate DMARC Authentication-Results
header DMARC_PASS Authentication-Results =~ /$escapedprimaryhostname; dmarc=pass/
describe DMARC_PASS DMARC check passed
score DMARC_PASS -0.1
header DMARC_NONE Authentication-Results =~ /$escapedprimaryhostname; dmarc=none/
describe DMARC_NONE DMARC record not found
score DMARC_NONE 0.1
header DMARC_FAIL_NONE Authentication-Results =~ /$escapedprimaryhostname; dmarc=fail \(p=none/
describe DMARC_FAIL_NONE DMARC check failed (p=none)
score DMARC_FAIL_NONE 2.0
header DMARC_FAIL_QUARANTINE Authentication-Results =~ /$escapedprimaryhostname; dmarc=fail \(p=quarantine/
describe DMARC_FAIL_QUARANTINE DMARC check failed (p=quarantine)
score DMARC_FAIL_QUARANTINE 5.0
header DMARC_FAIL_REJECT Authentication-Results =~ /$escapedprimaryhostname; dmarc=fail \(p=reject/
describe DMARC_FAIL_REJECT DMARC check failed (p=reject)
score DMARC_FAIL_REJECT 10.0
# Evaluate SPF Authentication-Results
header SPF_PASS Authentication-Results =~ /$escapedprimaryhostname; spf=pass/
describe SPF_PASS SPF check passed
score SPF_PASS -0.1
header SPF_NONE Authentication-Results =~ /$escapedprimaryhostname; spf=none/
describe SPF_NONE SPF record not found
score SPF_NONE 2.0
header SPF_FAIL Authentication-Results =~ /$escapedprimaryhostname; spf=fail/
describe SPF_FAIL SPF check failed
score SPF_FAIL 5.0
EOF
# Bayesean learning
# -----------------
#