Email to certain domains sitting in queue


  • I am seeing email destined for certain domains sitting in our Exchange 2010 queue with the following message:

    "451 4.4.0 Primary target IP address responded with: ""421 4.4.2 Connection dropped due to ConnectionReset."" Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts."

    I enabled SMTP logging and here's what I get when attempting to send to one of the domains in question:

    2012-06-12T14:23:35.685Z,External,08CF08634A19FB43,0,,External IP:25,*,,attempting to connect
    2012-06-12T14:23:35.763Z,External,08CF08634A19FB43,1,Internal IP:10158,External IP:25,+,,
    2012-06-12T14:23:35.841Z,External,08CF08634A19FB43,2,Internal IP:10158,External IP:25,<,220 Postini ESMTP 149 y652_pstn_c2 ready.  CA Business and Professions Code Section 17538.45 forbids use of this system for unsolicited electronic mail advertisements.,
    2012-06-12T14:23:35.841Z,External,08CF08634A19FB43,3,Internal IP:10158,External IP:25,>,EHLO,
    2012-06-12T14:23:35.841Z,External,08CF08634A19FB43,4,Internal IP:10158,External IP:25,-,,Remote

    One interesting thing to note, is that if I attempt to telnet to one of these domains from my Exchange server, it will initially connect by the moment I type e for ehlo, I immediately get a message "Connection to host lost". I also get the same result when attempting to telnet from my soon to be decomissioned Exchange 2007 transport servers. However, if I try to telnet to other domains such as gmail, comcast, etc. I am able to send a message without any problems. I am also able to telnet to the problematic domains from another linux server that we have on the network without any problems. Therefore, I believe this rules out any issues relating to a blacklist.

    Does anyone have any ideas of what to look at?

    Tuesday, June 12, 2012 5:49 PM

All replies

  • How is your email routing configured for outbound messaging?  Do you have a single Send Connector in EX2010 for all external domains?  Are you filtering outbound email through another application or hosted service?

    Tuesday, June 12, 2012 7:22 PM
  • Yes, we have a single send connector for all outbound messages. We do not send email through any other application. Email is sent directly from our transport server.

    Wednesday, June 13, 2012 12:41 PM
  • hi,

    >>>Therefore, I believe this rules out any issues relating to a blacklist.

    Yes, i think so. Can you contact to them and ask them if they have add your ip address into a blacklist.

    I think you should do it first.

    hope can help you



    TechNet Community Support

    Thursday, June 14, 2012 3:32 AM
  • hi,

    Any update?

    Have you check the blacklist?

    If your problem has been fixed, please remember to mark as answer.



    TechNet Community Support

    Monday, June 18, 2012 1:43 AM
  • Another possible cause for this could be a mismatch in your PTR / MX record for the mailserver. Lets say you have:




    In this scenario you will run into problems if your outgoing connection from the mailserver uses another ip address, say Make sure that the ehlo hostname, the outgoing NAT (if applicable) and the records for this server all match up.

    Monday, June 18, 2012 7:05 AM