DIAGNOSTIC PLAYBOOK
Null MX mixed with ordinary MX records
A null MX explicitly states that a domain accepts no mail and is intended as the domain's only MX record. Mixing it with normal mail destinations creates a contradictory configuration.
HealthCheck Email editorial team · · Examples are illustrative
How to investigate
- Inspect the complete MX answer, including a target represented by a single dot.
- Confirm with the domain owner whether incoming mail should exist.
- Keep the intended valid receiving configuration or the sole null MX record, then verify the public answer.
What this looks like
ILLUSTRATIVE EXAMPLE
A parked domain's null MX remains after a mailbox service is added. The zone simultaneously advertises no mail service and an active destination.
A mistake to avoid
Do not delete the no-service policy without confirming the new mailbox setup. DNS routing and recipient provisioning are separate steps.
Keep the result in context
The authoritative DNS service publishes records; recursive resolvers may retain earlier answers until their cache expires. Save the queried name, record type, resolver, answer and time. A website loading correctly does not establish that email records are present or that an SMTP server accepts mail.
Take the next step
Use the related check to gather evidence, then compare it with the affected message or service. Keep the result and time with your notes so a later change can be distinguished from the original problem.
Sources and further reading
The protocol references below explain the underlying behavior. Your sending or DNS provider supplies the account-specific settings for its service.