Question 1

How do I look up the MX records of a domain?

Accepted Answer

Enter any address at that domain above. DebounceNow performs a live DNS-over-HTTPS lookup and shows the MX hosts, their priorities, whether SPF and DMARC exist, and which mailbox provider the records belong to.

Question 2

What is an MX record?

Accepted Answer

An MX (Mail Exchange) record is a DNS entry naming the server that receives email for a domain, with a priority number deciding which host senders try first. Without a usable MX record, mail delivery is unreliable or impossible.

Question 3

What does a null MX record mean?

Accepted Answer

A single MX entry of "." is a null MX (RFC 7505): the domain explicitly declares it accepts no mail. Every address at that domain will hard-bounce, so they can be removed for free.

Question 4

Can I tell the email provider from MX records?

Accepted Answer

Yes. MX hostnames identify the provider — Google Workspace, Microsoft 365, Yahoo, Zoho, Proton, iCloud, Amazon SES, GoDaddy's secureserver.net and dozens more — which is how addresses are classified as business or free mailboxes.

Question 5

What if a domain has no MX record at all?

Accepted Answer

Some senders fall back to the domain's A record, so delivery is risky rather than always impossible. Parked domains resolve to a web host that cannot accept mail, so those addresses bounce.

Question 6

Is the MX lookup free?

Accepted Answer

Yes. DNS, MX, SPF and DMARC lookups are free and unlimited, with no signup or API key.

MX record lookup

MX hosts and priorities

Null MX and parked domains

Authentication records

Learn how MX records drive delivery

MX record FAQ