No Valid MX Record NDR message

Updated 4 years ago by admin

When you email a recipient over the Internet, the MX records specified in the domain DNS for the address you are sending to are checked. If those MX records are incorrect and point to an IP address defined as part of a private range or localhost (see RFC 1918), then the Email Security servers are forced to reject the email and cannot deliver it.

This is an issue with the way that the remote domain has configured the MX records. Unfortunately there is nothing that can be done through the Email Security product to fix this because the issue is at the remote side. If you encounter this issue, the best course of action is to contact the recipient or their email provider through other means and advise them of the problem.

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