A mail exchanger has no address

What it means

example.net is listed as a mail server for example.com but has no A or AAAA record, so nothing can connect to it. Mail either fails or falls back to a lower-priority host you may not be watching.

How to fix it

Publish an A or AAAA record for example.net, or remove it from the MX list if it is retired.

Check your own domain

This page describes the condition. To find out whether your domain has it, run the MX test or the full checkup, which examines every record at once.

Understand it properly

This page covers one condition. For the whole picture, Why mail lands in spam, in the order worth checking, or start at the Health Library.

Where this comes from

We judge this against RFC 5321 section 5.1. Every finding on this site cites the specification behind it so you can check the work rather than take our word for it.

Other MX conditions

• No MX records
• Domain declares that it accepts no mail
• MX record points at an IP address
• A mail exchanger is a CNAME
• Only one mail exchanger, on one address