Comment by sylware

You did truncate the context: you have to add email addresses with IP literals. This does change everything.

google is more than anything else (and this has been a few years) following its agenda at making email just a private garden of messaging with a few "chosen ones" of his friends (selection based on $$$). They are presuming de facto anybody who does not fit their technical agenda to be a spammer. This is the same with their "web" with their web engines from the 'whatwg cartel'.

An IP/domain becomes a source of spam until it does. And with their billions of $$$, I guess they have an army of guys to handle that properly: trying hard enough to notify the owner with data, etc. Yes, this is 99% of the work which has to be done at gmail.