Hi
I have an idea that Ironport also checks the IP of the actual sender as well as the Mail server they are sending through.




On Wednesday 16/02/2011 at 08:19:02, Case Hugo wrote:

We have a customer who can't seem to send to a domain that uses the Cisco Ironport.  It just disconnects our server.

We are listed as "good" on the senderbase.org  database.  Has anyone have any experience with this problem?  Is it possible that each Ironport checks its own send/receive symmetry.  I suspect (99% sure) that our customer sends to this Ironport on a regular basis but that the recipient replies back using another smtp server.  As soon as the "postmaster" from this domain started emailing me regarding this issue, the emails are going through.  (I suspect thus balancing the send/receive symmetry)

 

Am I on the right track or not? 

 

The "postmaster" claims his applience does not do any checking at all......  But if I am right the problem will be back as soon as the postmaster/support stops emailing me.

 

Thanks in advance.