How to Check MX Records and Read the Results

To check MX records, enter a domain in an MX lookup tool or query DNS directly. The result lists the mail exchangers that receive inbound email. Lower preference numbers are tried before higher numbers.

Run a lookup

1. Web: paste the domain, without a path, into Mailthentic MX Lookup.
2. macOS or Linux: run dig MX example.com.
3. Windows: run Resolve-DnsName example.com -Type MX.

The live Mailthentic tool returns hosts and a provider classification. It does not currently expose raw preference numbers, so use a DNS client when exact priorities matter.

Read priorities and backups

Priority controls route order. It does not measure quality.

Provider identification

MX hostnames often reveal Google Workspace, Microsoft 365, Yahoo, Zoho, Proton, Apple, a security gateway, or a self-hosted system. Provider detection is best effort because gateways can hide the final platform.

Troubleshooting

No MX record

Confirm the domain and query the root rather than a website hostname. SMTP can fall back to A or AAAA when MX is absent, but an explicit MX is clearer for a mail-receiving domain.

Null MX

A preference 0 record with exchange . explicitly says the domain accepts no mail. RFC 7505 defines it. This differs from a missing record.

Invalid hostname

An MX target must be a hostname, not an IP address. Check for an incomplete provider token or wrong DNS field.

Multiple priorities

This is normal for documented primary and backup routes. Investigate old providers left after migration.

Recent DNS change

Resolvers retain old answers until TTL expiry. Compare authoritative DNS with more than one resolver.

MX does not verify a mailbox

An MX record proves only that a domain advertises a route. It does not prove a mailbox exists or that a message reaches the inbox. Use the email checker for address signals and the domain checker for authentication context.

Continue with the SPF, DKIM, and DMARC tools.

Source

See RFC 7505. Last reviewed 2026-07-31.