MX Lookup
Find the mail servers for any domain. You get their priorities, IP addresses and reverse DNS, the email provider behind them, and checks for the mistakes that make mail bounce.
MX Lookup
How this lookup works. When you press Find mail servers, your browser sends the question over encrypted DNS-over-HTTPS to Cloudflare's public resolver (1.1.1.1), or to Google Public DNS (8.8.8.8) if you choose it below. The request goes straight from your device to them. It doesn't pass through ToolFeather: we have no server in the path, so we never see or store the names you look up. Requests are sent without cookies or a referrer. Each resolver has its own privacy policy: Cloudflare · Google.
Results appear here.
Queries your browser sent (0)
These are the exact requests, each one a link. Open one to see the raw JSON answer from the resolver.
Live lookup: your browser asks Cloudflare or Google DNS directly. Nothing passes through ToolFeather.
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How it works — in four simple steps
No signup and nothing to install — it all runs in your browser.
Enter a domain or address
The part after @ is used.
Press Find mail servers
Your browser queries the resolver directly.
Check the table
Priority, host, IPs, TTL and a status for every server.
Fix what's flagged
Each warning says what to change and why.
Lower the MX TTL to 300 a day before switching email providers, so senders pick up the new servers quickly.
Features
Priorities in order
MX hosts sorted by preference, with equal-priority load sharing called out.
Provider detection
Recognises about 35 providers, from Google Workspace and Microsoft 365 to Proofpoint and Mimecast gateways.
Addresses and reverse DNS
IPv4 and IPv6 for each host, plus the PTR name of its first addresses.
Error checks
IP-literal MX, CNAME targets, unresolvable hosts, mixed null MX and implicit MX.
Accepts email addresses
Paste jane@company.com and the domain is extracted for you.
About the MX Lookup
When someone emails you@example.com, their server looks up the MX records of example.com. Each record names a mail server and gives it a priority number. Lower numbers are tried first, and servers with equal numbers share the load (RFC 5321). The sending server then looks up each MX host's IP address and delivers there.
This lookup does the same steps from your browser. It fetches the MX records, resolves every host to its IPv4 and IPv6 addresses, checks the reverse DNS of the first addresses, and recognises the provider from the host names: Google Workspace, Microsoft 365, Zoho, Proton, Fastmail, Cloudflare Email Routing and around thirty others.
It also flags real-world errors. An MX pointing at an IP address instead of a host name isn't allowed. One pointing at a CNAME breaks RFC 2181 §10.3 and some senders refuse it. A host with no address can't receive anything. A null MX (0 ., RFC 7505) is the correct way to say a domain takes no mail: senders bounce at once instead of retrying for days. With no MX at all, senders fall back to the domain's own A record, the "implicit MX", which is rarely what anyone wants.