Earlier quoted context omitted.
Sadly, this says more about how broken GMail now is than anything else. Real Soon Now(TM), the tech community needs to start a serious campaign to shame and isolate email providers that do not reliably deliver legitimate emails, regardless of how high profile they are. It probably needs meaningful government/regulator backing to get anywhere. The odd false positive on spam/malware filtering is understandable, it's no…
It's more about how broken email is, gmail does what it does because they have to deal with the broken ecosystem of spammers and spoofers.
I don't really buy that excuse any more. This is a business that wants to have heavy, fast-moving objects automatically navigating complex and unpredictable transport networks using its software. For that matter, this is a business whose golden goose is prioritising content people most want to see on the scale of the entire WWW, which has no shortage of junk sites that exist primarily to game the system. I'm reasonably sure that same business can be smarter about spam recognition than defaulting to assuming new mail from a source it hasn't seen before is bad, which seems close to the practical output of its existing system. But as with so many of the current dominant tech businesses, until someone poses a credible threat to its existing business model and revenue streams, it has no reason to invest in fixing problems even if it could obviously do better.