Author: David Woodhouse Date: To: Eric Messick CC: exim-users Subject: Re: [exim] Sender verification, permanent vs. transient error codes
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?
