https://developers.cloudflare.com/email-service/reference/po...

Cloudflare is very transparent about their prefixes and reverse DNS, which is generally a good thing for the ecosystem! But it makes it trivial for operators who want to block the entire service, and extremely bad for Cloudflare's deliverability.

And while there are many open blacklists which I have no doubt Cloudflare monitors, there are many (including soft spam-classification signals) that are proprietary and difficult/impossible to monitor other than by watching rates of actual customer/prospect replies and engagement.

Amazon SQS has similar dynamics, and its reputation is far from stellar.

(If the Cloudflare team is reading this, and I'm missing an on-ramp to a company purchasing dedicated IPs with distinct PTR records, I do apologize! I'm not seeing documentation about this, though.)