Reverse DNS RRS feed

  • Question

  • Hi!

    While checking my Exchange 2007 on mxtoolbox i got a message

    "Warning - Reverse DNS does not match SMTP Banner."

    I have two mx records pointing to the same IP.


    Wednesday, March 23, 2011 10:50 AM


All replies

  • Hi,

    see this link:http://community.mxtoolbox.com/blog/2010/03/22/what-does-the-warning-reverse-dns-does-not-match-smtp-banner-mean-smtp-diagnostic-tool/


    best regards

    Best Regards Don't forget to mark it as answer if it helps
    • Marked as answer by Novak Wu Monday, March 28, 2011 2:13 AM
    Wednesday, March 23, 2011 11:25 AM
  • Hello,

    Anti-abuse mechanisms using reverse DNS records are sometimes employed by system administrators on their inbound mail flow to help fight forged email. First they will run a reverse DNS check on the IP that connected and compare that domain to the domain in the From: field of the email.

    An additional thing you can do, which is the focus of this thread, is to find the domain that the reverse record is part of and compare it to the domain from the SMTP Banner that is announced by the sender's email server and make sure that they match.

    Adding a reverse DNS record is an important thing to ensure mail delivery since checking for existence of a PTR is common and failure to have one could be dropped or bounced messages. It is not common (or a good idea in my opinion) to block mail simply for failing to match either the From or the Banner, but it might influence anti-spam scores negatively.

    Hope this sheds some light on the matter.


    Anouar KETAT
    My Blog: Directory Services
    Knowledge is only power if it's shared
    Thursday, March 24, 2011 3:22 PM
  • Hello,

    I have being doing this for awhile now and not sure if it has changed, but I always call my ISP and get them to set it up.   I had a friend who got me started with Exchange and told it was required.  Just call and give them your static and ask them to set up a reverse DNS entry for you.

    They do it right away like it is a standard question.

    Thank you,


    • Proposed as answer by phossil Thursday, March 24, 2011 10:04 PM
    Thursday, March 24, 2011 5:37 PM