Cadzow Knowledgebase

Normal view

Troubleshooting 5.4.4 Email Errors

Email sent to a particular domain may fail with the following error:

    Status: 5.4.4 (unable to route: no mail hosts for domain)

However, the receiver's domain is valid, and the MX is configured and resolves correctly. Furthermore, almost all email to the receiver is delivered correctly.

This may occur if the receiver's MX record is a CNAME. This configuration often works, but is not supported.

For example:

  1. The MX record is

  2. is a CNAME to

  3. resolves to an IP address.

In this situation the sender's mail server does not fully resolve the MX to the final IP destination.

To resolve, change the MX to

Note the changes will not take effect until the DNS timeout has expired on the MX record or the entire zone (usually 1-4 hours, but possibly up to 24).

In particular, MailChimp may generate “soft bounces” for domains with such an MX record.

Copyright © 1996-2023 Cadzow TECH Pty. Ltd. All rights reserved.
Information and prices contained in this website may change without notice. Terms of use.

Question/comment about this page? Please email