[exim] Inject email into Exim, get Return Code if Temporaril…

I would like give Exim a message to deliver to a remote host, and get
notified if Exim received a 4xx - Temporary Delay.

That is, if the messages is delivered successfully or bounces (5xx),
that is fine.

But I don't want messages sitting on the queue because there was a
temporary error. I want the spool queue to be empty at all times.

Does anybody have any ideas on how this might be possible with Exim ?

Thanks

mark