Re: [Exim] Temporary defer on callouts

On Fri, 2004-01-30 at 16:41 -0800, Bill Moseley wrote:
> I'd like to deny on timeout/temporary error, but I think that might be
> too extreme. So, I'm wondering if it would be possible to somehow give
> a temporary error, but cache the event and if they try again in an hour
> or longer then accept.
>
> The idea is that spammers may not try again on a temporary error, but
> legitimate mail would try again.
>
> Is something like that possible -- or even a good idea?

It's possible but not trivial to implement, and I'm not sure it's
necessary.

I do sender verification callouts, without defer_ok. It _does_ give a
temporary error on timeout/temporary error -- like for example if you
tried to send mail to me while your only MX host mail.hank.org was down.

For legitimate mail you're right that they'll try again later -- but
_also_, it tends to be the case that they'll to want to fix their own
incoming servers when they break.

So there's no real need for me to go to great lengths to remember that
you already tried to mail me, when I could just as well wait for you to
fix your mail server.

It's useful to exempt postmaster@ from this check (and indeed others) so
you can aid in diagnosis if necessary.

--
dwmw2