The difference is decided by decent spam filters: - is the exact same message being sent to many users? - does it look like previous spam? - are messages fro

The difference is decided by decent spam filters: - is the exact same message being sent to many users? - does it look like previous spam? - are messages from this host being reported as spam by users? We have plenty of techniques to filter out spam (those above and technical ones like DKIM to enable host reputation systems) and they mostly work great. What Google/Microsoft are doing is just monopolistic attitude and has nothing to do with spam filtering. Spam from big email servers is still common, but legit emails from smaller servers will not reach intended recipients, and will not produce any indication of that on either side of the communication. It's just silently going in the trash. If there was at least a decent way to get allowlisted on their side, we could give them the benefit of the doubt and accept that email ecosystem has turned to an opt-in federation model. But the way they do it and prevent recourse is a clear abuse of dominant position to crush the competition.