Does this mean that an email sent to an address that doesn't exist at a (non-email-service) websiteget delivered to somewhere else (the admin?) at that website, depending on how it's been set up?
For a fee, you can have all emails to your domain, regardless of what is before the @ emailed to you.
That's called "catch-all", and I pay nothing. It's a rule that has to be set up.
That's called "capture all", and I pay nothing. It's a rule that has to be set up.