NETCONFIG

MX Lookup

Check a domain's Mail Exchange records to troubleshoot email routing.

Quick presets

Mail Exchange Diagnostics

Enter any domain to inspect its published MX records and mail delivery priority order.

About the mx lookup

List the mail servers (MX records) of a domain in priority order. Use it to check where email for a domain is delivered and to spot setup mistakes after changing email providers.

Also searched as: MX record checker · mail server lookup · email server lookup · check MX records · find mail server of a domain

How MX priority works

Each MX record has a priority number. Sending servers try the lowest number first and fall back to higher numbers if it is unreachable. Equal priorities share the load.

Common problems

An MX record that points to an IP address instead of a host name, a missing record so mail falls back to the A record, an old provider still listed with a low priority, or a host name that has no address are the classic reasons for bounced or lost mail.

After a migration

When moving to Google Workspace or Microsoft 365, replace all old MX records. Leaving the previous provider in place splits mail between two systems.

How this tool works and how to read the results

What this tool does

Returns a domain's MX (Mail Exchange) records in priority order — the first thing to check when inbound mail isn't being routed to the expected mail server, or when setting up a new mail provider.

Reading priority values

Lower priority numbers are tried first. A domain with multiple MX records is typically using the lowest-priority one as primary and higher-priority ones as backups if the primary is unreachable — mail servers attempt delivery in that order automatically.

When you'd use this

Verifying a migration to a new email provider has fully propagated before decommissioning the old mail server, or diagnosing why inbound mail is bouncing or being misdirected.

Frequently asked questions

What does the priority number next to each MX record mean?

Lower numbers are tried first. Mail servers attempt delivery to the lowest-priority (most preferred) MX record, and only fall back to higher numbers if that server is unreachable.

Why do I see no MX records at all?

Either the domain isn't set up to receive email, or — a common misconfiguration — mail is actually configured on a subdomain rather than the root domain you looked up.

Can a domain legitimately have multiple MX records?

Yes, and it's normal — most domains list a primary and one or more backup mail servers so delivery can still succeed if the primary is temporarily down.

Can a domain have no MX records?

Then senders try the domain's A record, which rarely works. A domain that should not receive mail can publish a null MX (priority 0, target ".").

Why must an MX point to a host name?

The standard requires a name, not an IP address, and the name must not be a CNAME. Many servers reject mail otherwise.

How do I know my MX change worked?

Look up the domain here after the old TTL has expired and confirm only the new servers appear.

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