CriticalInfrastructure · usually critical
No MX records found
This domain publishes no mail exchangers, so it cannot receive email.
Check your own domain
What causes this
MX records tell other mail servers where to deliver mail addressed to your domain. With none published, a sending server falls back to the domain's A record in some implementations and simply fails in others. If this domain is meant to receive mail, this is a total outage.
What it breaks
Mail sent to addresses at this domain is not delivered. Senders receive bounces, and in many cases the bounce is a permanent failure.
How to fix it
Publish the MX records your mailbox provider specifies.
- Get the MX hostnames and priorities from your mailbox provider's setup documentation.
- Create one MX record per hostname at your root domain, with the priorities exactly as documented.
- If this domain is deliberately not used for receiving mail, publish a null MX record instead so senders fail fast and cleanly.
Related problems
- No email configuration of any kind was foundNo MX, SPF or DMARC records exist for this domain.
- MTA-STS is not configuredThe domain does not publish an MTA-STS policy. This is optional but worth having.
- MTA-STS record published but the policy file is unreachableThe DNS record announces a policy that cannot be fetched.
- An MX host does not resolve to an addressA mail exchanger is published but its hostname has no A or AAAA record.
- An MX record points at an aliasMX targets must be hostnames with address records, not CNAMEs.