RH (20) [Avatar] Offline
In section 6.2.6 (PDF page 103) there is a code sample that should (according to the surrounding text) illustrate how to report validation errors back to a sender via Status.Success and Status.Failure messages. However, the sample only shows Status.Success:
Receive<UserRegistrationInformation>(registration =>
  if (ValidInput(registration))
    var accountInfo = RegisterAccount(registration);
    Sender.Tell(new Status.Success(accountInfo));

It's possible that the ValidInput method is intended to send a failure message back to the sender of course, but it's probably nicer to make this more explicit.