Donaldson R F MX Lookup
See which mail servers receive email for a domain, in priority order, and which service runs them — Google Workspace, Microsoft 365, Proton, or the domain’s own server.
DNS lookups use a public DNS-over-HTTPS service (Google Public DNS, with Cloudflare as a back-up). Only the domain name is sent to it.
What MX records are
An MX (mail exchanger) record tells the world which servers accept email for a domain. Each record has a priority number and a server name: senders try the lowest number first and fall back to the others if it is unreachable; servers with the same number share the mail. If a domain has no MX record at all, mail can only be delivered by an old fallback rule that uses the domain’s web address, so a domain that should receive mail without MX records is usually misconfigured.
The provider is worked out from the server names (for example aspmx.l.google.com means Google Workspace or Gmail, and *.mail.protection.outlook.com means Microsoft 365). It shows who receives the mail, not necessarily who sends it, and a domain that filters mail through a security service will show that service. The MX records seen here are the ones published in the public DNS right now; recent changes can take up to the record’s TTL to spread.
Frequently asked questions
Why does it say a domain does not exist?
The DNS answered NXDOMAIN, meaning the name is not registered or not in DNS. Check the spelling.
What is a null MX?
A single MX record of “0 .” that a domain publishes to say it never receives email.
What is sent to the DNS service?
Only the domain name you look up. No email addresses or other data.