SMTP-Relay: add other ways of filtering

SMTP-Relay: add other ways of filtering

  - FROM is changed in all cases (as it was before...)
  - FROM isn't evaluated at all (as it was before)
  - FROM is looked up in the list of available email addresses, and corrected if not found.
  - FROM is looked up in the list of available email addresses, and if not found, relay access is denied.