Donaldson R F Email Provider by MX
Paste domains (or email addresses) and see which company handles each one’s email, worked out from its live MX records.
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.
How it works
For each domain the tool asks the public DNS for its MX records — the mail servers that receive its email — and matches the server names against a built-in list of providers (Google Workspace, Microsoft 365, Proton, Zoho, Yahoo, iCloud, Fastmail, GoDaddy, IONOS, Namecheap, OVH and security gateways such as Proofpoint and Mimecast, among others). A domain whose mail servers belong to itself is shown as Own mail server. Addresses are reduced to their domain, and duplicates are checked once.
This is different from the email provider detector, which only looks at the address (so jane@company.com looks like a business domain). Here we look at where the mail really goes, so a company on Google Workspace or Microsoft 365 is identified. To inspect one domain in detail use MX lookup; for its SPF and DMARC records use the SPF & DMARC checker. Lookups are limited per run to keep the public DNS service fair.
Frequently asked questions
Why are some domains “Unknown / other”?
Their mail servers are not on the built-in list — often a smaller host or a custom set-up. The MX host name is shown so you can look it up.
Does it send my domains to a server?
Each domain name is sent to the public DNS-over-HTTPS service (Google, with Cloudflare as a back-up) to look up its MX records; nothing else is sent, and nothing goes to our server.
Is the result always current?
It shows the public DNS records at the time of the check; recent changes can take a while to spread.