Header Checks
Apply cautious header-based actions before queueing or during cleanup.
Production note: Back up configuration, run
postfix check, and stage changes before reloading.Configuration
header_checks = regexp:/etc/postfix/header_checks
# header_checks
/^X-Unwanted-Header:/ IGNORE
/^Subject: test-block/ REJECT Policy testTest patterns
postmap -q "Subject: test-block" regexp:/etc/postfix/header_checksScope
Header checks are not a replacement for content filtering, authentication, or malware scanning.
Risk
Overbroad regular expressions can reject legitimate mail. Test representative headers before deployment.