Previously we relied entirely on levenshtein_distance_spammer_emails site
setting to handle "similar looking" emails.
This commit improves the situation by always preferring to block (and check)
canonical emails.
This means that if:
`samevil+test@domain.com` is blocked the system will block `samevil@domain.com`
This means that `samevil+2@domain.com` (ad infinitum) will be blocked