Postfix Email server - Host name doesn't match IP address [closed]

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Closed 9 years ago.

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I've got a postfix mail server setup on my VPS.

Just the other day when I sent an email I got it bounce back with the following error message:

Remote host said: 454 5.7.1 DXNS3 208.81.237.186: Message refused. Your host name dosen't match with your IP address: mx6-out.gaggle.net

Is this a problem with my server? By the way, my mail server isn't mx6-out.gaggle.net but it should be mail.onlythebible.com

So I'm a little confused as to what this error message means and how I can solve it. Thanks for any help with this issue.

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This is not a problem of your Postfix setup.

This is a problem of your DNS setup.

Let's assume that your Postfix is at mail.onlythebible.com. The IP to that name (the A Resource Record in DNS) is 173.255.234.40. So far so good. But there is a reverse way to get the name behind an IP. This is the PTR Resource Record in DNS. In your case this is set to li244-40.members.linode.com. And as you can see the names do not match: mail.onlythebible.com != li244-40.members.linode.com And this causes the weired error message.

The solution is to set the PTR in the DNS to mail.onlythebible.com. How (or if) you can do this depends on your hosting provider. You need to be able to edit the DNS configuration for the Reverse DNS Address (not the DNS configuration of the domain onlythebible.com). Please ask your VPS provider on how to set the PTR.