Regarding WCA Email blocking with local prefix, my client delete some of prefixes eg. "marketing@" from the list since they confirm these are appropriate mail addresses of their users. Even client delete the prefixes, the system restore the prefixes. Since they don't know the update time, client manually delete the prefixes every sending. It is really inconvenient and client complain about this. It is much useful if we can have a custom prefix lists for email blocking.