Quoth Philip Hazel on Sat, Feb 10, 2001:
> On Sat, 10 Feb 2001, Jeffrey Goldberg wrote:
> > As others have said, <> was invented for a reason. One of which is to
> > avoid loops.
I assumed that Marc knows what <> means.
> The other reason is that the callback test is supposed to check whether
> Exim could return a bounce to the sender. If you change the MAIL FROM
> address it uses, it is no longer doing that test.
And if both the MTA on the sender's MX record and the recipient
MTA use callbacks, this will cause "callback loop" -- sender
connects to recipient, says "MAIL FROM:", recipient connects to
sender, says "MAIL FROM:<postmaster@???>", sender
tries to verify postmaster, connects back to recipient, says
"MAIL FROM:<postmaster@???>", recipient tries to verify
postmaster, connects back... Ad nauseam.
[bounce messages]
> I'm beginning to agree with you. (Not that we don't see loops - some
> systems fish an address out of the body and use it. I even had one case
> where a forwarding system had fished an address out of the body and
> replaced the envelope sender with it as it forwarded the message.)
People who write such mailers should be... Ah, nevermind, on
this list everyone knows my pacifistic views on such people.
> > If you find that callbacks "need" this patch, then don't use callbacks.
>
> Or at least, use the options to turn them off for the mis-behaving
> hosts or domains.
This would be nice, but the question is where Exim should draw
the line and support no further brokenness on the side of the
abdominations it has to interface with on its line of duty. When
I look at all the features Exim has that have "WE DO IT BECAUSE
THAT OTHER MTA IS COMPLETELY BROKEN" painted on it with big red
shiny letters, I become slightly freaked off.
Vadik.
--
Avoid reality at all costs.
