The MX Lookup That Shows a Domain's Mail Provider.

An MX lookup, or mail exchanger lookup, queries a domain's DNS for its MX records, the entries that say which servers are responsible for receiving email for that domain. Type a domain into the tool above and Verifox reads those records back in priority order.

It answers three questions at once: does this domain accept mail, which provider runs it, and in what order servers are tried — the same DNS resolution our verification engine performs before it touches a mailbox.

A mail exchange record (MX record) is a DNS entry that points a domain's email to a mail server. Each record carries a hostname and a priority number, and a domain can publish several so there are backups if the primary server is unreachable.

The priority is a preference value: the lowest number is tried first. So a record at priority 1 is the primary mail server, and higher numbers are fallbacks. The format is defined in RFC 5321, and the MX lookup above lists them in that exact order.

The simplest way is to paste the domain into the lookup above and read the records back. No account, no install. You can also run nslookup -type=mx example.com or dig example.com MX in a terminal, but those return raw hostnames you have to interpret yourself.

Verifox names the mail provider in plain English, not just the hostnames, and flows into a real mailbox verification when you need to go past routing. Configuring a mail client? The IMAP and SMTP settings come from the same DNS records.

Three things. First, who runs the mail, the MX hosts reveal whether a domain is on Google Workspace, Microsoft 365, Proofpoint, or a self-hosted server. Second, how mail routes, the priority order shows the primary server and its fallbacks. Third, whether mail is accepted at all.

A domain with no MX record cannot receive email, an instant red flag for deliverability. To confirm a specific address is reachable, the mailbox itself has to be checked — a step no lookup alone can do.

A failed MX lookup usually means one of two things: the domain publishes no MX records, so it cannot receive email, or the domain itself does not resolve (a typo, an expired registration, or a DNS misconfiguration). Either way, mail to it bounces.

Some domains intentionally route mail without MX records, but for most, a missing MX means mail bounces. If the records look right but mail still fails, run an SMTP test against the server or check SPF, DKIM, and DMARC on the same domain.

Yes. The single lookup above is free with no account. For a list of domains, the REST API runs the same MX resolution as part of every verification call, so you can read the mail records behind a whole list of domains programmatically.

Bulk checks run on the same pay-as-you-go credits as the rest of the platform, localized to your region, and those credits never expire.

No, and the difference matters. An MX lookup checks the domain, can it receive mail at all, and who runs it. Verifying an email checks the specific mailbox, does [email protected] actually exist and accept mail.

A domain can have perfect MX records while a given address on it is dead. That is why the MX lookup is step one of deliverability and the free email checker is step two. Verifox runs both on the same engine.

No. The domain you enter is resolved in memory and discarded the moment the lookup completes. Nothing logged, nothing retained, nothing sold. A domain's MX records are public DNS data, but your queries are still yours.

Verifox is SOC 2 Type II compliant and GDPR ready. All queries run over encrypted DNS-over-HTTPS and nothing is retained after the lookup completes. Read the privacy policy for the full breakdown of what we log and what we do not.

Yes. Every call documented in the REST API reference runs the MX resolution as its first stage and reports the domain-level result, so you can wire mail-server checks into your CRM, your onboarding flow, or any tool that speaks REST.

Verifox also ships native MCP server support, so AI agents (Claude, Cursor, custom LLM apps) can look up a domain's mail records and verify addresses without glue code. Live uptime at status.verifox.ai is public for anyone auditing reliability.

For most domains, rarely. Moving from one mail provider to another, say Google Workspace to Microsoft 365, is the main reason records change, and even then the switch typically happens over a few hours as the DNS TTL expires. Day-to-day, the records are stable.

A sudden MX change on a domain you send to can mean it migrated providers, expired and was re-registered, or was compromised. Periodic mail domain lookups on high-value domains catch provider changes before they affect your bounce rate.