MX Lookup: Check Mail Exchange Records
What an MX lookup does
MX (Mail Exchange) records define which mail servers receive email for a domain. Every domain that receives email should have at least one MX record pointing to a valid mail host. If MX records are missing or wrong, messages bounce or never arrive.
An MX lookup is the first step when email is not arriving, when you are migrating to a new provider, or when you need to confirm that your registrar and DNS match your mail infrastructure.
You can run a full DNS lookup to see MX along with A, NS, and TXT, or use this focused MX lookup when mail is your only concern. After confirming MX, validate SPF and run an SMTP test to ensure the server accepts connections.
How to read MX results
Each MX record has a priority (preference) number and a target hostname. Lower numbers mean higher priority. Mail delivery agents try the lowest-numbered host first; if it is unavailable, they fall back to the next.
A healthy setup usually has at least two MX records with different priorities so that if the primary is down, the secondary can receive mail. Single points of failure are common in misconfigurations.
The target must be a hostname that resolves via DNS. If the hostname in your MX record does not resolve (check with a DNS lookup), delivery will fail.
Common problems and what to do
No MX records present: the domain will not receive email. Add at least one MX record pointing to your mail provider's host.
Old providers still listed: after migrating, remove or lower the priority of old MX records so mail does not go to decommissioned servers.
Typos in hostnames: a single character wrong in the MX target breaks delivery. Compare with your provider's documentation and fix the record.
Propagation delays: if you recently changed MX, different resolvers may still return old values. Use "Query all resolvers" to compare; our DNS lookup and NS lookup tools also support multi-resolver checks.
Next steps after MX is correct
Validate SPF so receiving servers know which hosts are allowed to send for your domain. Then run an SMTP test against your mail host to confirm the server is reachable and supports STARTTLS.
Keeping DNS and mail in good shape reduces bounces and improves deliverability; adding uptime monitoring for your mail and web endpoints helps you catch outages before users do.