It appears to be an unauthorized provider.
Addy aliases are temporary email addresses (aliases) that forward messages to their primary email account. This can help protect a user’s real email address from spam, unwanted marketing, or potential data breaches.
Less likely, sure. Still very possible? Yes. Not a risk I’m interested in taking.
You’re free to do what you want with your instance but you’re extremely naive if you think selling/leaking contact info is “tinfoil hat” territory.