Gmail spam filtering is top notch. I just stopped to care to obfuscate or hide my email adress (which I use since the beta invitation program of gmail) and I can count the spam I actually read in a year with one hand.
It classifies Stripe's and PayPal's important security emails as spam; I posted previously on HN:
https://news.ycombinator.com/item?id=19536465
It's easy to bring down the number of false negatives if you allow the number of false positives to be arbitrarily large.
On my GSuite business email, I've had > 50 incoming business-relevant emails this year that were incorrectly classified as spam. My personal self-hosted email server [1] lets through a bit more spam than Gmail, but it also doesn't suffer this big false-positive rate.
This is partly because Gmail is good at classifying emails as spam/ham.
But it's partly because it's more tolerant of false positives (ham sent to the spam folder) than you or I would be if we were tweaking our own spam filter.
I occasionally check my spam folder, and there are usually some mailing list emails that I don't care about, but which I did actually subscribe to, and would have wanted to reach my inbox.
I wish they'd apply that discrimination to their SMTP output.
gmail spam filtering is terrible. On my various gmail accounts, I both get spam and the good email goes to the spam folder. And there's nothing you can do, you can mark it not-spam a thousand times and it's still a crapshoot.
I don't have any of those problems with my self-hosted email.
