Echoing the base principle I see in other comments: proactively limit what can land in your inbox. I have a rule in Fastmail that only mail from senders in my contacts gets to inbox. If no rules apply, mail ends up in the firewall folder, which I check periodically.

I’ve been on a big unsubscribe wave for newsletters and notifications that I had previously opted into. If I haven’t been reading them within a week, they get dropped. Next step is to resume use of RSS for the topics I want to periodically check up on instead of crowding my email.

The other base principle is to segregate email addresses for personal correspondence and interactions with companies/services/accounts. I’ve not been good about that out of laziness. That’s more about data privacy and while most of my FnF still use gmail it is moot.

I’ve been a satisfied customer of Fastmail for several years. Based in Australia. Great features for email aliases, folders, and rules.