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Free Tool Lets You Check Whether Your Reverse DNS (rDNS) is Set Up Properly

This information is provided by SuretyMail Email Reputation Certification, getting email to the inbox for businesses of all sizes since 2003, guaranteed! For more information contact us here, or get started today here.

First, I want to apologize for not being around or posting here last week. I was on a week-long business trip, and while yes, I had a computer with me, I simply didn’t have the time to write. At least you know that it’s really me writing this, and not a ghost-writer, as is the case with some other CEO blogs!

Today I want to let you know about another free resource that we offer to the general public along with our customers: a free tool that allows you to determine whether your reverse DNS (rDNS) is set up properly.

Got questions about email deliverability or reputation? Contact us here!

As I’ve explained in more detail here, having your rDNS set up properly is really important. And having it not set up properly (or at all) can have a severe impact on whether the email you send gets delivered or not.

Briefly, rDNS is what allows a receiving email system to take your IP address, and see if it really maps to the domain that your email is supposedly coming from. It’s like Caller I.D. for email: where Caller I.D determines your name from your telephone number, rDNS determines your domain name from your IP address.

And if the domain associated with the IP address from which you are sending email doesn’t match what your email claims your domain should be (such as the “” in the email that I send), then odds are very good that your email will get rejected, or, if it is accepted, put into the junk folder.

This tool is very simple – you just type or paste the IP address in question into the form, and hit “submit”:

…and then it will show you where the rDNS for your IP address resolves:

If you don’t have rDNS set up at all, it will give you this message:

And if rDNS is not set up correctly – say it is set up to point to your ISP’s space instead of your domain, you’ll see something like this:

You can check your own IP addresses here at our free rDNS check tool.

This information is provided by ISIPP SuretyMail Email Reputation Certification, the only email reputation certification and deliverability assistance service with a money-back guarantee! For more information contact us here, or get started here.

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    I used the tool whatismyip and it showed my address pointing back to my ISP, CableOne. I am trying to get a ‘Net biz off the ground, with not a whole lot of luck so far. I have tons of email advertising to do. So…how would I change the rDNS?

  • Go to from the computer that is sending the email. That will give you an idea of what the outside world thinks is the ip of that machine. Now send an actual email to an account where you can see the full header of an email.

    Once you receive the email, it should have the generation ip address. If its the same as what you have above great, if not, you need a little more investigation.

  • I am in the process of designing my own website from a software package that is supposed to be “user friendly” for “non-techies” like me.

    Dumb question: How do I find out what my “IP” address is for my website email?

    Thanks for this tip!

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This article originally written on April 22, 2009, and is as relevant now as when it was first written.