How to use
01
Enter a domain or email address
Type example.com, or paste name@example.com and the part after the @ is used. Check the exact domain from the address, since a subdomain can have its own MX records.
02
Press MX lookup
The tool fetches the MX records, then resolves each mail server's addresses, reverse DNS and network owner, and reads the domain's SPF and DMARC records.
03
Read the checks and export
Look at the provider and health cards, the mail server table and the checks list. Copy the MX records for a ticket, or download the full table as CSV.
Why MX Lookup
- Lists a domain's MX records in priority order with TTL, IPv4 and IPv6 addresses for each mail server.
- Names the email provider behind the records: Google Workspace, Microsoft 365, Zoho, Proton and more.
- Checks reverse DNS, CNAME targets, null MX, and whether SPF and DMARC are published.
- Accepts a domain or a full email address. Copy or download the results as CSV.
What common email providers' MX records look like
The MX host names give away the provider. These are the patterns the tool recognises most often. Exact names can vary by region or account age, so follow your provider's setup page when you add records.
| Provider | MX host looks like | Notes |
|---|---|---|
| Google Workspace | smtp.google.com or aspmx.l.google.com | Newer setups use a single smtp.google.com record |
| Microsoft 365 | example-com.mail.protection.outlook.com | One record, named after your domain |
| Zoho Mail | mx.zoho.com, mx2.zoho.com, mx3.zoho.com | Regional variants end in .eu, .in or .com.au |
| Proton Mail | mail.protonmail.ch and mailsec.protonmail.ch | Two records with priorities 10 and 20 |
| Fastmail | in1-smtp.messagingengine.com | Two records, in1 and in2 |
| Cloudflare Email Routing | route1.mx.cloudflare.net | Forwards mail, usually three records |
| Mimecast or Proofpoint | *.mimecast.com or *.pphosted.com | Security gateway in front of the real mailbox |
Before you switch email providers
An email move goes wrong when MX records change before the new mailboxes are ready, or when the old ones are closed too early. Work through these steps in order.
- Create every mailbox and alias at the new provider first.
- Lower the TTL of your MX records to 300 seconds a day before the switch.
- Replace the MX records with the new provider's values and remove the old ones completely.
- Update SPF so the new provider is allowed to send, and set up DKIM signing there.
- Keep the old mailboxes open and check them for a few days while caches expire.
- Run this MX lookup and a DNS propagation check to confirm the new records are live everywhere.
Common questions
What is an MX record?
MX stands for mail exchanger. It is a DNS record that names the server that accepts email for a domain, together with a priority number. When someone sends you an email, their mail server looks up your MX records and delivers the message to the server listed there.
What does the priority number on an MX record mean?
Senders try the lowest number first. If that server does not answer, they move to the next number up. Records with the same number share the load. Hosted services such as Google Workspace and Microsoft 365 often need only one record, because they balance traffic behind a single name.
How do I find out who hosts a company's email?
Run an MX lookup on the company's domain. The provider card names services such as Google Workspace, Microsoft 365 or Zoho Mail from the MX host names. If the records point to a security gateway like Mimecast or Proofpoint, the mailbox provider behind it stays hidden.
What happens when a domain has no MX records?
Mail servers fall back to the domain's A record and try to deliver there, which the email standard calls an implicit MX. Web servers rarely accept mail, so the message usually bounces. A domain that should never receive email can publish a null MX instead.
What is a null MX record?
It is a single MX record with priority 0 and a target of a lone dot. Defined in RFC 7505, it tells senders that the domain accepts no email at all, so they bounce messages at once instead of retrying for days. Parked domains and web-only subdomains are good candidates.
Can an MX record point to a CNAME or an IP address?
No. The MX target must be a host name with its own A or AAAA records. Pointing at an IP address is invalid, and pointing at a CNAME alias breaks RFC 2181, although many servers tolerate it. The checks list flags both.
Why does reverse DNS matter for mail servers?
Receiving servers look up the PTR record of the IP that connects to them, and many distrust a sender without one, or one whose PTR name does not point back to the same IP. For MX hosts that only receive mail it matters less, but servers that also send your mail need it.
How long does it take for new MX records to work?
Until the old records' TTL runs out in resolvers' caches, often an hour and sometimes a day. Keep the old mailboxes working during that window so nothing is lost, and use the DNS Propagation Checker with the new mail server name to watch the switch.
Does an MX lookup tell me whether a mailbox exists?
No. MX records describe the whole domain, not individual addresses. The Email Validator checks an address's format and MX together, but only the receiving server knows whether a specific mailbox exists, and most do not say.