Cloudflare incident
Email Security delivery impacted by Spamhaus listing
Resolved after 2 hours 19 minutes, affecting Email Security (Area1) and Email Security (Zero Trust), on August 12, 2026.
All IPs previously listed by Spamhaus are now clean. Monitoring the propagation of that change to downstream systems.
Affected components
Update timeline
- investigating Aug 12, 2026, 03:04 PM UTC
We are currently investigating an issue where customers that use Spamhaus for additional filtering of email downstream from the Cloudflare Email Security service are rejecting emails from IPs in the 134.195.26.0/23 block. This IP block should be allowed for all customer downstream systems to avoid treating the Email Security service as an originator of mail. We recommend all Cloudflare Email Security customers disable Spamhaus filtering in downstream systems.
- investigating Aug 12, 2026, 03:07 PM UTC
We are continuing to investigate this issue.
- investigating Aug 12, 2026, 04:30 PM UTC
We are continuing to investigate this issue. Customers using O365 will be impacted only if they have not completed the required setup. Please check your setup and ensure the connector includes all egress IPs: https://developers.cloudflare.com/cloudflare-one/email-security/setup/pre-delivery-deployment/prerequisites/m365-email-security-mx/#2-configure-enhanced-filtering
- monitoring Aug 12, 2026, 04:48 PM UTC
All IPs previously listed by Spamhaus are now clean. Monitoring the propagation of that change to downstream systems.
- resolved Aug 12, 2026, 05:23 PM UTC
This incident is now resolved.
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