Free tools / MX Lookup
MX record lookup
MX records tell the world which servers accept email for a domain. If they are missing or wrong, mail to that domain bounces. This tool returns the records in priority order and identifies the mail provider behind them, which is often the fastest way to learn what a company runs on.
The provider guess is useful beyond troubleshooting. Knowing that a prospect is on Google Workspace versus Microsoft 365 tells a sales team which integration to pitch, and knowing that a domain routes through Proofpoint or Mimecast tells a cold email sender to expect stricter filtering.
What you get back
MX hosts. Every mail exchanger for the domain, sorted by priority. The lowest number is tried first.
Mail provider. Google Workspace, Microsoft 365, Proofpoint, Mimecast, Zoho, GoDaddy or other, inferred from the hostnames.
Deliverability signal. No MX at all means the domain cannot receive mail, which is why the email verifier uses this check.
How to use it
- Enter the domain, or paste a full email address.
- Press Look up MX. The query goes straight to DNS.
- Read the provider line. For a migration, confirm the new host shows with the lowest priority and the old one is gone.
Who uses this
IT admins. Confirming a mail migration or diagnosing why a domain is bouncing starts with the MX records.
Sales and SDR teams. Provider detection segments a list by Google versus Microsoft shops before the first email.
Deliverability consultants. Security gateways in the MX chain predict how aggressive the filtering will be.
Same check, in your code
One API key, one credit pool, 1,000 free lookups to start. Phone, email, IP and DNS checks from a single endpoint, and you only pay for lookups that return an answer.
Start free Read the docsQuestions
The domain has no MX records but they receive email. How?
Without MX records, mail falls back to the domain's A record. It works, but it is fragile and most verification tools treat it as undeliverable. Add proper MX records.
What does the priority number mean?
Lower is tried first. Equal priorities are load balanced. Backup servers get higher numbers.
How is the provider detected?
From well-known hostname patterns. Google uses aspmx.l.google.com, Microsoft uses mail.protection.outlook.com, and so on. Custom hostnames show as Other.
Is this cached?
Results are cached for one hour. For a migration you are watching minute by minute, use dig or the API with a cache-busting parameter.