MX Lookup
Enter a domain name to look up its mail servers, priority order, and email provider.
MX Record Lookup
What Are MX Records and How Does Email Routing Work?
An MX record, short for Mail Exchanger record, is a DNS entry that names a domain’s mail servers. It tells the internet which servers accept email for that domain. When someone emails user@example.com, their mail server first runs a DNS lookup to find the MX records for example.com. Those records point to one or more mail server hostnames, such as mail.example.com or aspmx.l.google.com. The sending server then connects to that destination to deliver the message.
Without MX records, a domain cannot receive email at all. Even if the website is live and working, email delivery fails silently when MX records are missing or wrong. MX records are entirely separate from the A or CNAME records that control web traffic. That separation is why a domain can host a website on one server while routing all its email elsewhere. A common example is running the website on a web host while using Google Workspace or Microsoft 365 for email.
How to Read MX Priority Values
Every MX record includes a priority number, sometimes called a preference value. This number controls the order in which mail servers are tried. A lower number means higher priority. The sending server always attempts delivery to the lowest-numbered host first. If that server is unreachable or returns an error, the next-lowest server is tried. Delivery continues down the list.
For example, a domain with two MX records might have:
- Priority 10 — mail.example.com (primary, tried first)
- Priority 20 — backup-mail.example.com (fallback, used only if priority 10 fails)
When two records share the same priority value, the sending server picks between them at random. That spreads load across servers. Google Workspace uses this pattern across its five MX hosts to balance incoming email. This tool sorts results by ascending priority, so the first row is always the server senders contact under normal conditions. When the records match a known provider, a banner above the table names it.
Common Use Cases for an MX Lookup
Troubleshooting email delivery problems is the most frequent reason to run an MX lookup. If email to your domain is bouncing or being rejected, first verify the MX records exist. Confirm they point to the correct mail server. A missing record, a hostname typo, or a record still pointing at an old provider are all common culprits. Pair an MX lookup with the Email Auth Checker to verify routing and authentication in one session. That covers SPF, DKIM, and DMARC.
Verifying mail server setup matters when you configure a new email service for the first time. After you add MX records at your registrar or DNS host, propagation takes time. It can run from a few minutes to 48 hours. A lookup here confirms the records are live and correctly formatted before you test email flow. You can cross-reference the mail server hostname against what your email provider told you to expect.
Checking after a domain migration is critical. It applies whenever you move to a new registrar, switch DNS providers, or change email platforms. During a migration, MX records are among the most important to verify. Even a brief misconfiguration can bounce or silently drop incoming email. For a complete post-migration audit, combine this tool with a full DNS Record Lookup. That confirms A, NS, and TXT records transferred too. If you recently moved a domain, the Reverse DNS Lookup helps confirm hostname resolution matches your new setup.
Frequently Asked Questions
What is a good MX record priority setup?
Lower numbers are tried first, so the primary server gets the lowest value. A simple setup is priority 10 for the main server and 20 for a backup. Hosted providers handle this for you. Google Workspace, for example, ships five servers at priorities 1, 5, 5, 10, and 10.
Why shouldn’t I have MX records from two providers at once?
Mail flows to whichever server has the lowest priority number, so mixing providers splits or misroutes your email. A leftover record from an old host is a common cause of mail landing in the wrong mailbox. When you switch providers, remove every old MX record before adding the new ones.
How long do MX record changes take to work?
A change takes effect once the old record’s TTL expires in resolver caches. That is often under an hour, but it can take up to 24 to 48 hours worldwide. The TTL column here shows the cache lifetime in seconds. Use a propagation checker to confirm the new record is live everywhere.
Related Tools & Resources
For a full view of a domain’s DNS configuration, use the DNS Record Lookup. To verify email authentication — SPF, DKIM, and DMARC policies — use the Email Auth Checker. To build SPF and DMARC records from guided options, use the SPF and DMARC Record Generator. To confirm DNS changes have propagated across public resolvers, use the DNS Propagation Checker. To check a site’s certificate, use the SSL Certificate Checker. For registration and ownership details, the WHOIS Lookup has you covered. Browse the full collection at the networking tools hub.