Only Pawnmail staff have @pawnmail.com email addresses. Domain owners can register email addresses under their own domain (such as @joesmith.com), which may or may not contain filtered words.
However, you have a good point. It would probably not be the ideal name for a service like to GMail, in which all users live under the @gmail.com domain.
Irrespective of whether users use their own domain, email sent through the pawnmail service will be associated with the pawnmail domain via their MX records.
However, you have a good point. It would probably not be the ideal name for a service like to GMail, in which all users live under the @gmail.com domain.