Free DNS tool

MX Lookup

Look up the mail exchange records for any domain, see the priority order and resolved IP addresses, and confirm your inbound mail has somewhere to go.

No login required. We query live DNS and never store your domain.

Try it instantly

Look up MX records for a well known domain, or enter your own above.

Next steps after MX
rDNSCheck reverse DNSSPFCheck your SPF recordGradeFull reputation report
MX records, explained

What is an MX record?

An MX record, short for mail exchange record, is a DNS entry that names the mail server responsible for accepting email for a domain. When someone sends a message to an address at your domain, their mail server queries DNS for your MX records to learn where to deliver it. Each record holds two pieces of information: a priority number and the hostname of a server that handles your inbound mail.

Every domain that receives email needs at least one MX record. Without one, other mail servers have no published destination for your incoming messages, and delivery either fails or falls back to behavior you did not intend.

How mail routing uses MX priority

The lookup happens in real time as mail is sent. The sending server reads the recipient domain, fetches its MX records, and connects to the host with the lowest priority number first. Priority is a preference value, so a lower number means a more preferred server. RFC 5321 defines this behavior as part of the SMTP standard.

  • Lowest number wins. A record at priority 10 is tried before one at priority 20. The values are relative, so only their order matters, not the exact numbers.
  • Equal priorities share load. When two hosts carry the same priority, sending servers pick between them at random, spreading inbound mail across both.
  • Failover is automatic. If the preferred host refuses the connection or times out, the sending server moves on to the next priority in line.
  • Hostnames, not addresses. An MX target must be a hostname that resolves through an A or AAAA record. RFC 5321 does not permit an IP address literal as an MX target.

Multiple MX records and redundancy

A domain can publish as many MX records as it needs, and most production setups use at least two. A second mail exchange at a higher priority number acts as a backup: if the primary is unreachable, sending servers queue and retry against the secondary instead of bouncing the message. Many managed providers handle this redundancy for you behind a single hostname, which is why a one record setup is not always a problem.

When you do run your own backups, leave gaps in the priority numbers, such as 10 and 20, so you can slot a new server in between later without renumbering everything.

Common MX mistakes

  • Pointing an MX at a CNAME or a bare IP. The target must be a hostname with its own address record. A CNAME or an IP literal breaks strict senders and is disallowed by RFC 5321.
  • A single MX with no backup. One host is a single point of failure. If it goes down, inbound mail waits in sending queues until it comes back.
  • Hostnames that do not resolve. If an MX target has no A or AAAA record, sending servers cannot connect and mail fails even though the MX record exists.
  • Stale records after a migration. Old MX entries left behind after switching providers can route mail to a server that no longer accepts it.

MX records only control where inbound mail is delivered. They say nothing about whether your outbound mail is trusted. Pair this lookup with the SPF record checker for sender authorization and the reverse DNS checker for PTR alignment on your sending IPs, then run the full sender reputation checker to grade everything together.

Frequently asked

MX record questions

What is an MX record?
An MX record, or mail exchange record, is a DNS entry that tells other mail servers where to deliver email for your domain. Each record pairs a priority number with the hostname of a server that accepts your inbound mail. When someone emails an address at your domain, their server looks up your MX records and connects to the most preferred host. Without an MX record, a domain has no published destination for incoming mail.
How do I check or look up MX records?
Enter your domain in the tool above and it queries live DNS, sorts every mail exchange by priority, and resolves each host to an IP address. To check from a terminal, run dig +short MX example.com on macOS or Linux, or nslookup -q=mx example.com on Windows. Both return the priority numbers and hostnames published for the domain.
What does MX priority mean?
Priority is a preference number on each MX record, and the lowest number is tried first. A host at priority 10 receives mail before a host at priority 20, which only takes over when the first is unreachable. The values are relative, so 10 and 20 behave the same as 1 and 2. When two records share the same priority, sending servers split inbound mail between them at random.
Can a domain have multiple MX records?
Yes, and most domains that take email seriously publish at least two. Extra records at higher priority numbers act as backups, so mail fails over to a secondary host instead of bouncing when the primary is down. If several records share one priority, they also balance load. Many hosted providers deliver this redundancy behind a single hostname, so one visible record can still be backed by multiple servers.
What is a good MX setup?
A healthy setup has at least one MX record pointing to a hostname that resolves to a valid IP, ideally with a second host for failover. Leave gaps in the priority numbers, such as 10 and 20, so you can add servers later without renumbering. Never point an MX record at a CNAME or a bare IP address, and confirm that every hostname has a working A or AAAA record. If you use a managed provider, match their published values exactly.
Why are my MX records not working?
The usual causes are DNS propagation delay after a recent change, a typo in the mail server hostname, the wrong priority order, or old records left behind from a previous provider. Confirm your records match what your mail provider specifies, check that each hostname resolves to the correct IP, and remember that changes can take up to 48 hours to appear everywhere. Re-run the lookup above until the new values show.
Do I need an MX record to send email?
An MX record governs where your domain receives mail, not whether it can send. A domain can send outbound email without one. That said, many receiving servers treat a sending domain that cannot also receive mail as suspicious, so most legitimate senders publish MX records anyway. To be trusted on the sending side, focus on SPF, DKIM, DMARC, and matching reverse DNS on your outbound IPs.
What is a backup MX record?
A backup MX is a second mail server listed at a higher priority number than your primary. If the primary is unreachable, sending servers move on to the backup, which accepts and queues your mail until the primary returns, so messages wait in a queue instead of bouncing. Many managed email providers build this redundancy in behind a single hostname, so you do not always need to configure a separate backup yourself.
What MX priority number should I use?
The exact numbers do not matter, only their order, since the lowest number is always tried first. A common convention is 10 for your primary server and 20 for a backup, leaving gaps so you can slot another server in later without renumbering. If you want two servers to share inbound mail evenly, give them the same priority and sending servers will pick between them at random.
Can an MX record point to an IP address?
No. An MX record must point to a hostname that has its own A or AAAA record, not to a raw IP address and not to a CNAME. RFC 5321 disallows both, and strict receiving servers will reject a message rather than deliver to a malformed target. If you only have an IP, create a hostname with an A record first, then point the MX at that hostname.
Do MX records affect my outbound email or sending reputation?
No. MX records only tell other servers where to deliver mail addressed to your domain, so they govern inbound delivery, not how your outbound mail is judged. Your sending reputation depends on authentication, blacklist status, reverse DNS, and engagement instead. Correct MX records are still part of a complete, trustworthy DNS setup, which is one of the signals receivers weigh overall.
Keep exploring

Related tools & resources

Hand-picked next steps for this topic: checkers, guides, and plain-English definitions that go deeper.

Tool Reverse DNS Checker Confirm your sending IP has a valid, matching PTR record. Guide DNS Records for Email Configure MX, SPF, DKIM, DMARC, and PTR records the right way. Term MX Record A DNS record specifying which mail servers accept email for a domain, along with priority values. Term Mailbox Provider A service hosting email accounts and managing incoming mail delivery. Examples: Gmail, Outlook, Yahoo Mail. Tool Sender Reputation Checker Get a free A to F reputation score across authentication, blacklists, DNS, and infrastructure.