Reverse DNS for MX check

Posted on 2009-02-09
Last Modified: 2012-05-06
Hello Everyone,

Quick question for you.

I have an Exchange 2007 server (running on Server 2008) and everything works great.

A few places reject our email, not many but a few. It's a 554 reject "Spam Message not queued".

I have a theory that it has to do with my reverse DNS.

Here's my setup:

Exchange 2007 which is "mailserver.domain.local" send out through a barracuda spam appliance (barracuda.domain.local).

My MX record of course points at the barracuda with the host address of ""
which has an ip address of

Now, a reverse DNS check resolves to speakeasy address of:


My question: Should the lookup resolve to "" ?

My theory is that because it's not resolving straight back some mail servers (again very few) are listing us a "spam" and not delivering our messages.

Please let me know if I'm off my rocker here or on the right path.

Thank you! Happy Monday!

Question by:IncubusJax
    LVL 9

    Accepted Solution

    You can contact speakeasy and they can help you change the reverse DNS of their IP address.

    You should also setup SPF for your domain:
    LVL 11

    Assisted Solution

    yeah you would require Reverse DNS aka Reverse Pointer records. in addition you need SPF records as well. Please check if your outbond IP address is listed on any RBL sites ( check on

    Author Comment

    Thanks Gentlemen,

    Looking into these ideas right now... I will let you know how it goes soon.


    Author Closing Comment

    Excellent, Many thanks

    Expert Comment

    To test your Reverse DNS settings use this site

    also here is an SPF test tool, and more other. I use this site every day to test any servers

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