Author: Eric Messick Date: To: exim-users Subject: Re: [exim] Sender verification, permanent vs. transient error codes
On 1/25/07, David Woodhouse <dwmw2@???> wrote: >
> On Wed, 2007-01-24 at 16:02 -0800, Eric Messick wrote:
> > They open a connection from port 40774 to my port 25, sending SYN.
> > I reply with SYN ACK.
> > They reply with ACK, completing the opening of the connection.
> > They send FIN ACK, immediately closing the connection.
> > I reply to the initial open with an ACK, followed by the text "220
> > syzygy.com ESMTP".
> > I then notice that they've closed the connection and send FIN ACK.
> > They reply to my last ACK and data packets with a pair of RST packets,
> since
> > they closed the connection without waiting for this data.
>
> I suspect a broken firewall. Since it doesn't seem to happen when I
> connect to the mailhost for syzygy.com, I suspect a broken firewall at
> _their_ side. Can you get them to show a tcpdump of their end of the
> conversation?
I'll see if I can get one.
I believe that mail from their server to mine works just fine. Their
firewall would have to be stopping their outgoing connection only when in
the middle of an incoming one from me. That doesn't seem plausible to me.
