How EXACTLY to add an email PTR Record?

My outbound emails are getting blocked by Microsoft Email servers. I want to add a PTR record that might fix the problem.

If my IP Address is, I think the “name” for my DNS record should be and the value should be mail. example. com
Is that right?
Or should my name be and the value be
Or something else?

You can only create reverse records if you are the actual owner of the IP block.

If your host owns the IP, you need to create the reverse record in their menu.

If you actually own the IP, you can follow the instructions given here:


Thanks for the quick reply Laudian. We don’t own the IP (the mail server is owned by mailgun). My understanding that is that I need to create an A record in my dns, give it a name like mailgun. example. com, and point it toward the dedicated IP address that mailgun provides me. Then mailgun will create the reverse PTR record as you indicated.

No, Mailgun will not create a PTR record specifically for you.

I can almost guarantee you that the IP from which your emails are sent is shared with many other customers, but there can only be one PTR record. That PTR record will point to Mailgun, not to any of the customers.

Can you test your mail with and link the result here? That would quickly show most problems with your mail setup.

Or do you actually have a dedicated IP address? I’d assume you have an IT department if you are big enough to have a dedicated IP address for your mailserver.

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We do have a dedicated IP address. And mailgun gave us the instructions to create our A record, then they will create the PTR on their side. We are a small org, and not a huge number of emails, but it seems the dedicated IP was needed to get better “scores” for our emails(I think).

In that case, all you need to do is create the A record you were asked to create. You are not involved in creating the PTR record at all.

However, Mailgun themselves recommends the following regarding dedicated IPs:

As a “small org”, I’d assume you sent much less than 100k mails per month?

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Thanks Laudian, you are correct again. We average about 1,000 emails per day. Looking through our records we obtained the dedicated IP address in 2019 at mailgun’s recommendation to resolve the continual problems we were experiencing using their shared ip addresses. We are still waiting for them mailgun to set up the PTR to see if that resolves the problem. Microsoft claims they don’t see any rejection for our emails, yet our error messages (S3150) clearly come from Microsoft and we are also pursuing this problem with them, which began at midnight this morning.

S3150 seems to indicate that your IP address is on a blocklist by Microsoft.

This often happens when Microsoft blocks entire IP-blocks (no pun intended), though it is obviously possible that your IP was blocked specifically.

I really doubt these issues are in any way related to Reverse DNS.

Call me old-fashioned, but if a service provider fails to provide the agreed upon service, that’s hardly something that would encourage me to spend more money on the same provider.

And as you (might) experience right now, a dedicated IP does not help you if the whole IP range is blocked due to bad reputation.

I would still try the test at quickly. All you do is send an email to them, and none of the information that can be seen in the results is private in any way. Anyone you send emails to can see that information.

Any problems shown there are easy to fix and can have a huge impact on reputation.

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Thanks Laudian, I did try www. mail-tester. com. That is a great resource! We scored a 9.3. We don’t have DMARC. There are other minor changes we could/should make, but I think they are unlikely to solve this problem. The problem started today, so it is pretty clearly a change made by Microsoft. We are currently advising clients not to use a `hotmail or outlook or any Microsoft related email address.

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