Free MX Lookup
Check the mail servers for any domain live from your browser, see who runs them, and confirm it can receive email. Free, with no signup.
Domain
Look up the MX (mail server) records for any domain, live from your browser through Cloudflare's public DNS resolver, and see who runs them. Free, with no signup.
How it works
Enter a domain
Type any domain, like company.com.
Run the lookup
We query DNS live for the domain's MX records.
Read the results
See each mail server and its priority, lowest first, and who runs it.
Verify addresses
Confirm a specific mailbox is deliverable before you send.
Check any domain's mail servers
MX records are the DNS entries that route email to the right servers. Looking them up tells you whether a domain can receive mail at all, and which provider (Google, Microsoft, etc.) runs it.
This free MX lookup queries DNS live from your browser, lists the mail servers in priority order, and names the mailbox provider or security gateway behind them, handy for diagnosing delivery issues or vetting a domain before you reach out.
MX exists ≠ the inbox exists
A domain having MX records means it can receive email, but it doesn't mean a specific address is real. Catch-all domains accept everything and tell you nothing.
When you need certainty about an individual address, it has to be verified mailbox by mailbox.
At volume, a form is the wrong shape for that check. Emailchaser verifies every address on your list in bulk before a campaign sends, and 1Lookup exposes the same check as a bulk email validation API you can call over a whole list from your own code. 1Lookup is built by the same team as Emailchaser.
The MX record also tells you nothing about who is on the other end of a specific address. If that is the question you actually have, you can look up the owner of an address from the address itself: the name the local part encodes, the company the domain belongs to, and the public pages it appears on.
How to read MX record priority
Every MX record carries a priority number, and lower means higher priority. A sending server always tries the record with the smallest number first, and only falls back to a higher number if that server can't be reached. So a domain publishing 10 mail1.example.com and 20 mail2.example.com routes everything to mail1 unless it goes down, then fails over to mail2.
When two records share the same priority, mail is balanced roughly evenly between them. Google Workspace is the textbook example: it lists 1 aspmx.l.google.com, then 5 alt1.aspmx.l.google.com and 5 alt2.aspmx.l.google.com, then 10 alt3 and 10 alt4. The single priority-1 host is the primary; the paired 5s and 10s are equal-weight backups. The results above are already sorted lowest-first, so the top row is the server that actually receives the domain's mail.
Which email provider does a domain use?
The MX hostname usually gives the provider away, which is handy for tailoring a cold email or diagnosing a bounce. A domain whose MX ends in .google.com (aspmx.l.google.com) runs on Google Workspace; one pointing at a tenant such as company-com.mail.protection.outlook.com is on Microsoft 365. Zoho Mail shows mx.zoho.com, Fastmail uses messagingengine.com, and iCloud custom domains resolve to icloud.com hosts.
Watch for a security gateway sitting in front of the real mailbox. MX records ending in pphosted.com or ppe-hosted.com are Proofpoint, mimecast.com is Mimecast, iphmx.com is Cisco Secure Email and ess.barracudanetworks.com is Barracuda. In those cases mail is filtered by the gateway first and then handed to Google or Microsoft behind it, so the MX tells you the filter, not necessarily where the inbox itself lives. The lookup above applies the same rules and names the provider under the raw records.
Inbox Rules Index
Who handles inbound mail for the 499 business domains we measure: Proofpoint 33.9%, Microsoft 365 26.1%, Google Workspace 18.8%, Their own servers, or unknown 9.6%, Mimecast 4%. A domain with a security gateway in front of Microsoft 365 or Google Workspace counts as the gateway, because that is the software that reads the message first.
Measured Saturday, 5 September 2026 across 499 real business domains, 10 measurements since 2026-08-10.
On each measurement we look up the published email settings of the same 499 real companies, the kind you send cold email to. This is what they have set up, not a score on your own sending. It does not predict where your mail lands: that is judged against your own domain's records.
MX records vs deliverability: what this check can't tell you
An MX lookup confirms that a domain can receive mail and reveals who runs it, but it says nothing about whether your messages will reach the inbox. Deliverability is decided by your own domain's authentication and reputation, not by the recipient's MX. A domain can have flawless MX records and still send your email straight to spam.
If you're troubleshooting your own sending, MX is only the first check. From there, confirm your SPF, DKIM and DMARC records are valid and aligned, and that your sending IP and domain aren't blacklisted. Emailchaser's free email deliverability test runs those checks together, and the SPF, DKIM and DMARC generators help you fix anything that's missing.
Sending history is the part no DNS check can show you. A mailbox that has never sent anything has no reputation to spend, which is why warming up the sending mailbox belongs on the same checklist as the records above.
Why isn't a domain showing any MX records?
The most common reason is that the domain simply isn't set up to receive email, a parked domain, a redirect-only domain, or one bought purely for a website. Under the mail-routing spec a server with no MX may fall back to the domain's A record (the same address the website uses), so a handful of domains still accept mail without an MX, but you shouldn't count on it.
Before assuming a domain is dead, rule out the simple causes. Make sure you entered the root domain (company.com), not a subdomain or a full email address. MX records live on the root, though this tool already strips a leading www or @ for you. If the domain was just registered or its DNS was just changed, the records may not have propagated yet. And a single record pointing to a bare dot is a null MX (RFC 7505): a deliberate signal that the domain sends mail but will never accept it.
Related free tools
Common questions about MX records
What is an MX record?
An MX (Mail Exchange) record is a DNS record that tells the internet which servers handle email for a domain, and in what priority order. If a domain has no MX records, it generally can't receive email.
How do I check a domain's MX records?
Enter the domain above and click look up. The tool queries DNS live, lists the mail servers with their priorities, lowest number first, and names the provider or security gateway the hosts belong to (Google Workspace, Microsoft 365, Proofpoint, Mimecast and so on). It's the quickest way to see who hosts a domain's email.
Why does MX matter for cold email?
Before sending to a domain, MX records confirm it can actually receive mail. They also reveal the email provider, which helps you tailor sending. A missing MX is a red flag that the address will bounce.
Is the MX lookup free?
Yes, it's free and needs no signup. The lookup runs from your browser using a public DNS service.
What do the priority numbers on MX records mean?
The number is a preference value, and lower wins. Sending servers try the MX with the lowest number first and only fall back to higher numbers if it's unreachable, so the lowest-numbered host is the primary mail server. Records that share the same number are used interchangeably to balance the load.
How can I tell if a domain uses Google Workspace or Microsoft 365?
Look at the MX hostname. Google Workspace domains point at aspmx.l.google.com and its alt hosts (anything ending in google.com), while Microsoft 365 domains point at a tenant name ending in mail.protection.outlook.com. If you instead see pphosted.com, mimecast.com or similar, a security gateway is filtering the mail before it reaches the real provider behind it.
What happens if a domain has no MX record?
In most cases mail to that domain bounces, because there's no server advertised to receive it. A sender can technically fall back to the domain's A record when no MX exists, but many providers no longer do this, so a missing MX usually means the address is undeliverable. A single MX pointing to a bare dot is a null MX, which explicitly declares that the domain never accepts email.
Do MX records affect email deliverability?
MX records control where email is routed, not whether it lands in the inbox. Your deliverability depends on your own domain's SPF, DKIM and DMARC setup, your sending reputation and your content, not on the recipient's MX. Use an MX check to confirm a domain can receive mail, then a deliverability test to see whether your mail will actually arrive.
How long do MX record changes take to take effect?
MX changes propagate according to the record's TTL, commonly between 5 minutes and an hour. Resolvers that already cached the old record keep using it until that TTL expires, so switching providers can take anywhere from a few minutes to a day to be visible everywhere. Lowering the TTL a day before a migration makes the cutover much faster.
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