ProtonMail has a free tier. It's definitely not the same level of service as Gmail, but I prefer it to being so dependent on the big G juggernaut for a critical service.
Downsides:
* spam detector is a bit aggressive, sometimes legitimate emails make it in there.
* features are limited unless you pay.
Full disclosure: I pay for their Plus product. My rationale is that I pay twice as much per month for Netflix yet email is hugely more valuable to me than Netflix is.
More full disclosure: I used to work for Google. That's part of what made me move from Gmail.
I'd argue that if ProtonMail's spam filter is too aggressive then basically you're in the same place you were with Gmail, aren't you? (Except now you're paying?)
The issue described in the OP is email not even making it to the spam folder. If it at least makes it to ProtonMail's spam folder, that's an improvement.
Downsides:
* spam detector is a bit aggressive, sometimes legitimate emails make it in there.
* features are limited unless you pay.
Full disclosure: I pay for their Plus product. My rationale is that I pay twice as much per month for Netflix yet email is hugely more valuable to me than Netflix is.
More full disclosure: I used to work for Google. That's part of what made me move from Gmail.