Re: [exim] Re: bounce messages and their potential misuse

Peter Bowyer wrote:
>>>We're talking about an outbound relay sending to arbitrary
>>>destinations, with verified senders. Callouts are a waste of time,
>>>because it can deliver a bounce to the known sender if it's unable to
>>>deliver a message.
>>
>>Which known sender would this be?
>
>
> The one which it authenticated, or which an upstream trusted MTA
> authenticated. It's an outbound relay for a known community of users.

Ah, sorry; first time I've seen authentication mentioned.
The original just said "accepting anything from a list of
known IPs".

With auth, yes, accept-then-bounce is permissable (but still
suboptimal, I think. I prefer, as a user, an instant error
to my mistyping a destination address. As a networking engineer
I prefer the fewer number of connections).

- Jeremy