When I receive a command in my inbox that I have processed, I don't want to replay that message if it is not idempotent, as it may have side affects.

But what about producing the same messages downstream that I sent. It may be that the message was resent from upstream because someone downstream of me needs to reprocess it, but they can't do that unless I resend the messages I sent.

So it should be possible to configure the inbox to replay associated messages in the outbox that were raised when we received that command, from the outbox. To do that we simply have to clear the dispatched indicator in the outbox so that the sweeper will resend (we don't need to support immediate send here, if you don't have a sweeper its unlikely you also want this kind of support.