How do I check the MX record of a domain?

Paste any address at that domain into the free validator — it performs a live DNS lookup over DNS-over-HTTPS and shows the MX hosts, their priorities and the mailbox provider they belong to.

What happens if a domain has no MX record?

Delivery is unreliable or impossible. Some senders fall back to the A record, but parked domains and null-MX domains cannot accept mail at all, so those addresses hard-bounce.

What is a null MX record?

A single MX entry of "." that declares the domain accepts no email. It is defined in RFC 7505 and means every address at the domain will bounce permanently.

Do MX records affect deliverability?

They determine where your mail goes and which provider's filters it faces. They do not authenticate you — that is SPF, DKIM and DMARC — but a missing or misconfigured MX on your own domain breaks replies and bounce handling.

What is an MX record?

Updated September 3, 2026

An MX (Mail Exchange) record is a DNS entry that names the server responsible for receiving email for a domain, with a priority number deciding the order senders should try them. No usable MX record means no email delivery.

How to read an MX record

Each record has a priority and a hostname, for example "10 aspmx.l.google.com". Lower priority numbers are tried first; the rest act as backups. Senders resolve the hostname to an IP and connect over SMTP.

What a null MX record means

A single record of "." with priority 0 is a null MX (RFC 7505). It is the domain explicitly declaring that it never receives mail — common for domains used only for websites or for sending. Any address on a null-MX domain is a guaranteed hard bounce.

What MX records tell you about a mailbox

MX hostnames identify the real provider behind an address: google.com hostnames mean Google Workspace, outlook.com hostnames mean Microsoft 365, and there are recognisable patterns for Yahoo, Zoho, Proton, iCloud, Amazon SES, GoDaddy's secureserver.net and dozens more.

That classification is what lets you separate free mailboxes from business domains and segment sends per provider.

No MX record but mail still works?

Some senders fall back to the domain's A record when no MX exists, which is why an MX-less domain is risky rather than always impossible. Parked domains, however, resolve to a web host that cannot accept mail at all.

Try it on your own list

Run the free validator on any address or CSV, then spend credits only on the addresses that survive.

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Frequently asked questions

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