He has separate email addresses on a custom domain.

He then gives one of those separate emails to humans.

Companies he orders from gets another email address.

Social media companies get another one. Etc.

- a while back I tried to apply this principle in my gmail - filter everything not from a human out of my inbox using rules and filters (filtering anything with the word “unsubscribe” works well until someone forwards a thread to you that started with an email from a service).

It is a little frustrating though, I’m sure gmail and most modern email services could do a very good job on a filter like this if they tried.

No, it‘s not perfect — but if something slips through, I‘ll sort it out manually.

I use a separate address that I only give to people. Never use it for forms or sign-ins, and if anything marketing-related makes it there it's instantly spamboxed.