So with Proton pass, I create a new email alias for every online account. It will be formatted like mycustomalias.randomword12345@passmail.com. I set the text on each to the name of the site I make it for.

If I get an email to one, it goes to my hidden "main" address, which I haven't given out to a single person on earth, not even my wife. When I get an email, I can reply to it using the alias. The sender cannot ever see my main email.

This has a few benefits. One, nobody knows who I am. A website cannot link me to another site. If there's a data leak, one single email address is leaked. I can easily delete that alias and make a new one. Similarly, if I EVER get a spam email, I know which alias it was sent to, so I know who leaked it, or who decided to send me spam. Again, I can delete it and the spam source is gone.

Unlike something like "myemail+customalias@gmail.com", which does allow me to use different emails for each place, this is untraceable. You cannot find my main email by looking at an alias.

And finally, this is more anonymous than using your own domain, as you share the same domain as many other people.

When I use Proton pass the password manager, it can generate one of these aliases in about 1 second and ties it to that saved password for super easy log in. No other configuration requird. It just works. (you can use and create aliases without passwords if you want)