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.

An Ironport is just an email filtering appliance.  In that sense, not much different that the Barracuda that we use here at LCR.

When this happens again(if it does), from your surgemail server telnet to port 25 of the ironport and see what it tells you or how it reacts to doing that.  Usually that tells volumes about what is going on.

I suspect that somehow your server or email sender was being blocked by the Ironport and their postmaster cleared that without telling you what he did.

Lyle Giese
LCR Computer Services, Inc.