> Setting limits (...) makes it harder to abuse services with those identities. Almost no legitimate users actually need truly unlimited email addresses (...). Even generous limits would help to avoid many problems.

Note that Relay already rate-limits customers:

> we limit our free users to 5 total aliases, and we rate-limit our premium customers so they cannot create large-scale throw-away aliases for abusive sign-ups and behaviors.

https://github.com/wesbos/burner-email-providers/pull/339