Add signature to the generated email aliases.

Problem: when an email that uses catch-all is exposed, bad actors could try to send spam to addresses that are not tied to a specific website or service (like when using website@mydomain.com).

Signatures in the alias would make it so that any email that does not match the signature is rejected. If the alias is modified (like when trying to guess an email to send to my domain), the email is simply discarded.

The alias could look like the following: webiste-{signature}@mydomain.com

More info/Original idea from https://kevincox.ca/2022/07/07/signed-email-addresses/