Exchange 2003 issue. Email bounces back when trying to send an email

Posted on 2007-07-26
Last Modified: 2011-09-20
we are trying t send an email to domain but the email bounces back.
Their IT dept sent us the following reply. What exactly do we need to do ?


...Their mail server is failing our DNS verification test.  Their outbound mail server is  That address maps back to the name, but that name is not in the DNS.  They need to fix their DNS.

Here is an excerpt from a web page still under construction which explains the problem in more detail.  The text is still rough, but it gets the point across.

    Our servers perform a simple DNS verification on the IP address of
    each inbound SMTP connection. A reverse lookup is performed on the
    address to get its name, and that name is then looked up to get an
    address. If the two addresses don't match, or if either of the DNS
    queries fails, then this is considered a suspicious condition and the
    sending host is allowed to send us only one recipient per hour.

    In general, we do not grant exceptions to this rule. A DNS
    verification failure almost always indicates an error in your DNS
    configuration, which needs to be fixed. If you can demonstrate that
    your DNS is correct and that some other factor is leading to a false
    positive under this rule then we can exempt your server.

Question by:c_hockland
    LVL 8

    Assisted Solution

    Does your mx record have a ptr?
    LVL 8

    Expert Comment

    Point to return.

    Author Comment

    On the external DNS my MX record doesnt have PTR.
    On the internal DNS i think it does. i need PTR (Reverse in Linux) on both external and Internal DNS ??
    Thanks both of you in advance.

    LVL 104

    Accepted Solution

    Do you send email directly or via your ISPs SMTP Server?
    If you send email directly then you need to ensure that you DNS is configured correctly.
    Put your domain in to and see if it flags any errors in the mail server section.

    The message that you have received looks like it is doing a reverse lookup check, so I suspect that you either don't have one, it is invalid or it doesn't match what the server is announcing itself as.


    Featured Post

    IT, Stop Being Called Into Every Meeting

    Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

    Join & Write a Comment

    Get an idea of what you should include in an email disclaimer with these Top 5 email disclaimer tips.
    Find out how to use Active Directory data for email signature management in Microsoft Exchange and Office 365.
    The video tutorial explains the basics of the Exchange server Database Availability groups. The components of this video include: 1. Automatic Failover 2. Failover Clustering 3. Active Manager
    The basic steps you have just learned will be implemented in this video. The basic steps are shown to configure an Exchange DAG in a live working Exchange Server Environment and manage the same (Exchange Server 2010 Software is used in a Windows Ser…

    728 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    23 Experts available now in Live!

    Get 1:1 Help Now