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Delayed Messages and then NDR

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  • Delayed Messages and then NDR

    I have some users trying to send mail to what appears to be a free email provider in China ( They are receiving admin messages stating that the mail delivery is delayed and then end up receiving a NDR. No problems sending mail any where else.
    I've been looking into this and I think it relates to this company setting up their service beyond the normal scope to protect from spam. But I am not sure what change to make in my setup to get around and not screwing anything else up in the process.
    My MX record points to my IP. There is a corresponding PTR record. My email server is servername.AD-domainname.local.
    I see this in my SMTP log.
    450 4.7.1 <servername.AD-domainname.local>: Helo command rejected: Host not found
    If I am reading this right they are reverse checking or forward checking the servername.AD-domainname.local and not able to verify it since it is different then my MX record. Sound like I am going down the right path?
    I found something about changing the FQDN of the Default SMTP Virtual Server under Advanced in delivery from servername.AD-domainname.local to But I'm thinking that will screw up something DNS wise and DNS is no strong suite for me. But is this barking up the right tree and if so, can someone clarify what DNS changes would need to be made and whether they are internal (AD integrated) and/or external DNS (ISP). More details the better. is sent to my IP, goes through my firewall to a Barracuda, which forwards good mail to my exchange server. Outbound goes straight through out to the net from the exchange server. Although it is not SBS, this server is also running multiple other roles (DC, File, etc). This will be changing later this year.

  • #2
    Re: Delayed Messages and then NDR

    Well it kinda looks like the problem might be at the other end. Using gives me:

    Step 1: Try connecting to the following mailserver: -

    Step 2: If still unsuccessful, queue the E-mail for later delivery.
    Trying to connect to all mailservers: - [Could not connect: Connection closed before I received all my data]

    Their server might have a problem...



    • #3
      Re: Delayed Messages and then NDR

      Yes, was thinking so as well, but want to be sure. My exchange is 2003 SP2.