What’s the relationship between Spamhaus and major ISPs?

Spamhaus has established relationships with most major mailbox providers and ISPs. Its data is widely trusted and frequently consulted in filtering decisions.

Providers like Gmail, Microsoft, and Yahoo incorporate Spamhaus data into their filtering systems. A listing on SBL, XBL, or DBL affects deliverability at these destinations, though each provider applies the data differently.

The relationship is based on Spamhaus's track record of accuracy and its nonprofit, anti-abuse mission. Providers trust Spamhaus because its criteria are documented, its false positive rate is low, and it does not accept payment for delisting.

This trust makes Spamhaus listings particularly impactful. While other blocklists matter, Spamhaus is the one that virtually every significant destination consults.

Spamhaus speaks with authority that every major harbor respects. Their word carries weight throughout the shipping lanes.