SpamAssassin can query SpamHaus via DNSBL lookups, but which IP it tests depends on the Received chain and rule set, so a listed early relay often goes unnoticed.
Read MoreResolve Debian Postfix rejecting external emails by fixing inet_interfaces and smtpd_recipient_restrictions.
Read MoreFixes external email rejection and outgoing mail failure in Debian Postfix by correcting the smtpd_relay_restrictions parameter order.
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