On Sat, 2009-05-16 at 13:55 +0800, W B Hacker wrote:
> David Woodhouse wrote:
> > I've just encountered a host which seems to temporarily firewall me for
> > a minute or two after I give it a bogus RCPT TO:.
> >
> > So what happens is this:
> >
> > Exim connects and does a random callout, which is correctly rejected.
> > On sending RSET, it just gets a TCP FIN back. Exim attempts to make
> > another connection, and its SYN packets are just ignored.
> >
> > Five minutes later, the sender tries again. This time, the random
> > callout result is cached, so Exim goes straight to verifying the _real_
> > address. The verification passes, and the mail is accepted.
> >
> > Perhaps we should be doing our callouts in the opposite order -- the
> > real address (which we expect to succeed) before the random address
> > (which we expect to fail)?
> >
> > Yes, that means that in the case where the random address _does_
> > succeed, we're pointlessly checking the real address too. But only once,
> > and we're still doing it all in only a single connection.
> >
>
> Try it both ways against [email protected], then again against
> [email protected]
>
> I'll check the logs and let you know what we are seeing here.
The former just gives me this on connection (to 203.194.153.81):
451 Temporary local problem - please try later
The latter works fine; gives this in the callback exchange:
220 ESMTP Sat, 16 May 2009 14:30:13 +0800
HELO twosheds.infradead.org
250 triligon.to Hello twosheds.infradead.org [90.155.92.209]
MAIL FROM:<>
250 OK
RCPT TO:<[email protected]>
550-
550 Mis-typed or Invalid address or wrong address format.
RSET
250 Reset OK
MAIL FROM:<>
250 OK
RCPT TO:<[email protected]>
250 Accepted
QUIT
221 triligon.to closing connection
--
dwmw2
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