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

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. Affected customers should ask their Proofpoint administrator to allowlist notify.cloudflare.com and Cloudflare IPs 104.30.16.2,104.30.16.3,104.30.16.4,104.30.16.5,104.30.16.6, and 104.30.16.7. If this cannot be configured locally, contact Proofpoint for additional support.

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