I'm always stunned at how good GMail's spam filtering is, at least for me. I've been using the same email address since 1996 - that's 30 years now - and posting it with absolutely no thought to spam protection all over the place.
I get ~1000 spams per day. About 1-2 end up in inbox. Every so often I do go through my spam, and while it's possible I've missed something, I generally find less than 1 false positive a month and it's never anything especially important.
I've started to question if GMail's spam folder is marketing more than substance. I've used the same primary email address for nearly the same number of decades. The time I saw the "most" spam in a spam folder was only while it was hosted on Google Workspace. Actually trying to skim through those "1000s per day" a lot of them seemed suspect in strange ways (why was this even delivered anywhere?) and some of them even seemed like Google just dumping random ad copy from legitimate search ads into the folder.
(Also it says a lot that right now my two biggest sources of daily spam are Google Calendar Notifications and Random Firebase Accounts. Both of those further leave me questioning if Google's approach to spam filtering is sincere.)
I’ve had the same gmail address since it was first announced. It also gets email forwarded to it from another ancient email address that I used to self-host and that still gets occasional real mails. Most of the spam is addressed to that other address.
Just took a peek at my spam folder: 207 messages going back to March 18th, two false positives (both from mailing lists), but nothing critical. I think maybe I’ve seen one spam message across all my accounts in my inbox. Their filters benefit from a huge set of trainers on their data.
(As an aside, I would note that some newer addresses that I publish naked on some websites that I maintain get very little spam (14 messages between the two accounts in the same timeframe, most of which are from a single sender who decided that they should send me their press releases without any means of opting out.)
I've been a Fastmail customer for years and have been pretty happy with their spam filtering too. Anything that does get through either gets a custom rule to send it to the shadow realm, or gets sent to a special "Learn spam" folder that I set up which will train the spam filter on that message.
Have you noticed decreases over time by sending thigns to the "Learn Spam" folder? I'm a relatively new Fastmail customer - I setup a domain for some family accounts that I can manage on behalf of my aging family members so it's not receiving a lot of email _yet_ but I expect it to in the future.
I have noticed it for sure. The default spam filter catches most of what I'd consider spam, but the Learn Spam feature is needed for things that get through because they look legitimate. For example, I get a lot of those weird "You're an American, I'm from [China, India, etc.], we can make a lot of money if you go to all the interviews/meetings and then let me do all the work" kind of emails. They look like normal correspondence (maybe they are) so they occasionally end up in my inbox. When they do, I send them to the "Learn Spam" folder, and the next time I check my actual Spam folder I'll find that Fastmail caught several more just like it and sent them straight there.
Fastmail here too, and my email address is older than Gmail, and probably older than a significant portion of HN posters. Fastmails spam filter just works. I get a few false negatives per month, and some months zero. I've set it to /dev/null the most obvious spam, and I can't recall the last false positive. It's happened, but extremely rarely. Google spam filter is not unique or magical.
And I never liked Gmail the client. It's not as godawful as Outlook, nothing even comes close, but it always gets in my way and does things in weird Googly ways. I'll stick with Kmail, thanks.