I am not a Google employee, but I do work with email anti-spam at scale. There's a lot to critique here but it boils down to three points: 1. Spam filter behavior has changed because spam has increased in volume and sophistication, not because ISPs want to save money, or to eliminate competition. Some techniques that worked well 5 years ago aren't as effective anymore. One of the consequences of this has been a reduc…
> The filtering behavior reported here is either misunderstood or misrepresented. First, no, no major ISP (Gmail, Yahoo, Microsoft/Outlook, icloud) is going to permanently block an IP range; filters are designed to be dynamic. In severe, ongoing, high-volume spam scenarios, you could see a 2-week block, maybe occasionally 30 days. But never "one strike". You say you're knowledgable, but I also ran my own email server…
If you find yourself in an IP range involved in a severe, ongoing, high-volume spam scenario that's affecting your delivery, then it means your provider is not managing IP range reputation, or not doing it very well, and you should vote with your dollars and move somewhere else.
As a rule of thumb, email-specific service providers tend to do a better job of managing IP range reputation than more general purpose providers like VPSes.