Cannot Receive Email – Troubleshoot DNS

domain-name-systememailemail-server

I'm somewhat green when it comes to network administration, and I'm having some trouble configuring my DNS records so that I can receive e-mail to an e-mail server that I've recently set up. I'm able to send e-mail from the server, I'm just not able to receive mail. The e-mail server is an instance of the Standard Edition of MailEnable. The domain name for the server is of the form mydomain.com. I'm trying to set up the e-mail server to use the sub-domain mail.mydomain.com. Both of these domains point to the same IP address, and everything is running on the same server. When I type in the domain mail.mydomain.com, one of MailEnable's online tools produces an error message which reads:

FAIL, Unable to determine name servers for this domain. This may be
because the domain is not registered. Please see www.dnsreport.com for
more information on this domain.

This leads me to believe that this is a DNS issue. Could anybody point in the right direction as to how to troubleshoot this? I'm able to successfully ping mail.mydomain.com. Also, when I type nslookup mail.mydomain.com, I'm able to retrieve the mx record

mail.mydomain.com MX preference = 5, mail exchanger =
mail.mydomain.com

I'm not really sure what to do, or how to proceed in troubleshooting the issue…

Any help will be much appreciated!

Andrew

Best Answer

The domain name for the server is of the form mydomain.com. I'm trying to set up the e-mail server to use the sub-domain mail.mydomain.com.

I'm assuming that the mail in mail.mydomain.com is really a host, and not a domain. If it is a real sub-domain, you're going to have issues with your setup.

Both of these domains point to the same IP address, and everything is running on the same server.

If you want smooth-running email, you're going to need (at a minimum) in your DNS entries:

  • A valid DNS A record to map the host to the address
  • A valid DNS PTR record to map the address to the host; while not technically necessary, many mail systems enforce the concept of reverse-lookup to determine if the connection received is valid or not. This record will be in your reverse-lookup zone, not your forward-lookup zone.
  • A valid MX record, which should point to mail.mydomain.com in your example

However, you go on to show this:

FAIL, Unable to determine name servers for this domain. This may be because the domain is not registered. Please see www.dnsreport.com for more information on this domain.

This is a problem with your DNS setup in general. You haven't specified a name server for the domain...when a client (or mail server) attempts DNS queries, the net result is "there isn't anyone to talk to". The name server for the domain is a "hint" to others that, when asking about a host in the domain, they should go there.

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