Cloudflare Access one-time PIN emails blocked by certain email security gateways, including Proofpoint

lowCloudflareAccessSep 1, 2026 20:06

authenticationsecurity

Security IncidentAuthentication Issue

Summary

Some customers using email security gateway like Proofpoint may experience delayed Cloudflare notifications and login codes. Proofpoint is temporarily deferring messages with an SMTP 421 4.7.0 response. Cloudflare will continue retrying delivery.

Impact

minor

Timeline

Sep 1, 2026 20:06

[investigating] Some customers using Proofpoint may experience delayed Cloudflare notifications and login codes. Proofpoint is temporarily deferring messages with an SMTP 421 4.7.0 response. Cloudflare will continue retrying delivery.

via statuspage

+0m

Sep 1, 2026 20:06

[investigating] Some customers using email security gateway like Proofpoint may experience delayed Cloudflare notifications and login codes. Proofpoint is temporarily deferring messages with an SMTP 421 4.7.0 response. Cloudflare will continue retrying delivery.

via statuspage

Lessons Learned

⚠Cloudflare has experienced 367 incidents in the past year. This frequency suggests systemic reliability challenges that may warrant additional monitoring.

📊Incidents related to authentication, security have occurred 202 times across all providers in the past year. This is one of the most common failure categories in cloud infrastructure.

💡This incident is categorized as: Security Incident, Authentication Issue. Consider implementing preventive measures specific to this failure category.