> I run an email sending service at scale (billions of messages per month, tens of millions of end users, thousands of customers).

Giving you the benefit of the doubt and accepting your claim, doesn't that make you one of the people at least second-order responsible for the current state of affairs in email blocking? It would seem that your company, by dint of your volume, navigates roadblocks that the rest of us (ie. the 99.999% of Internet email servers and their admins), who aren't FAANG et al[1], have to deal with to get our users' legitimate email delivered.

If so, could you perhaps give us a brief explanation as to why an otherwise competent engineer can "follow all the best practices" with their server which has no known compromises[2], on an IP address they have controlled for, oh, let's say a full calendar year, and yet still can't get off those FAANG et al default-deny blocklists, but you can?[3]

A cynic might say that your service had a vested interest in paying for unimpeded access to those FAANG et al companies to get over the bar that the rest of us are unable to vault. A cynic might also say that those biggest of the big email services like it that way, because it drives more users to them at the expense of the rest of us 99.999%.

I'll try to remain open to the possibility that there are aspects of the industry I've not yet had any exposure to, and refrain from chimping out over having my users blocked through no fault of their own.

[1] Yes, I know, Facebook doesn't receive anywhere near as much email as they send, and Hotmail = Microsoft, etc. If I used an accurate acronym I could pat myself on the back for being Technically Correct, while nobody would know what the heck I was talking about.

[2] We shan't digress into a discussion of hardware/firmware/OS/application backdoors nor Snowden disclosures. It's not that hard to auto-install security updates and run a reasonably tight ship with no unnecessary attack surfaces.

[3] Or perhaps there aren't any default-deny blocklists at all, but in fact only much smaller default-allow whitelists? That would be cynical indeed.