trading fours:
> I am seeing the subjected error for a small percentage of messages, and
> then those message stay in the deferred queue.
>
> from the log:
> postfix/local[1124]: warning: unexpected protocol delivery_request_protocol
> from private/bounce socket (expected: delivery_status_protocol)
You changed the 'bounce' service entry in master.cf, and replaced
the bounce program name with the name of some program that does not
implement the delivery_status service protosol. Don't do that.
Also, you are receiving mail, presumably via SMTP, and then bouncing
it. Don't do that.
Wietse
