DIAGNOSTIC PLAYBOOK
MX hostname has no A or AAAA record
An MX record needs a destination hostname that resolves to a usable address. Publishing the MX text alone does not create the receiving server or make its address resolvable.
HealthCheck Email editorial team · · Examples are illustrative
How to investigate
- List every MX target and resolve its A and AAAA answers.
- Compare missing names with the receiving provider's exact documented hostnames.
- Correct the target or restore its address records, then verify SMTP reachability separately.
What this looks like
ILLUSTRATIVE EXAMPLE
A domain publishes mail.example.com as its MX target, but that hostname has no address record. Senders know the intended name but have no IP to contact.
A mistake to avoid
Do not insert a guessed server IP into the MX value. MX data contains a preference and hostname, while address records belong at the destination name.
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.