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Deliverability & Blocklists
Spamhaus Starts Enforcing HELO and Reverse DNS Checks on Sending IPs
From November 2026, Spamhaus is gradually requiring every sending IP to have a valid HELO, a PTR record and a matching A record. Here is who is affected and the checks to run before your IP lands on CSS or XBL.
- Announced: 21 October 2026, in the Spamhaus Sender Guidelines
- Enforcement: gradual rollout starting November 2026, over several months
- Requirement: a valid HELO, a PTR record and a matching A record for every sending IP
