Hi,
At work we have a Cisco Pix firewall running 7.x code.
We have an issue in that the external company providing a spam filtering service is having difficulty sending us mail via the TLS connection over port 25.
Their protocol logs show the response to the "data" command from our servers, and it looks like it is sending us a partial message, but we then time out the connection with a 4xx response.
I checked that we don't have the Cisco ESMTP inspection switched on on our firewall, but the guys providing the antispam solution are saying that it may be possible somewhere our firewall is dropping some of the packets.
Has anyone come up against something similar before, and knows where best to look?
Thanks. Andrew.