TinyPingTinyPing

MX Lookup

Find which servers receive email for a domain: each MX record in priority order, its TTL and the IP addresses of every mail server. Enter a domain such as example.com.

Common MX record problems

No MX records found

Without MX records, sending servers fall back to the domain's A record and try to deliver there, which usually fails or bounces. If the domain should receive email, add the MX records your email provider gives you. If it should not, publish a null MX.

Null MX (".") on a domain that should receive mail

An MX record of "0 ." (RFC 7505) tells senders the domain accepts no email at all. It is correct for parked or web-only domains, but if it was left in place after setting up a mailbox, every message bounces. Replace it with your provider's MX records.

MX record points to a CNAME

RFC 2181 says an MX target must be a hostname with its own A or AAAA records, not an alias. Many senders tolerate it, some do not, and delivery becomes unreliable. Point the MX at the real mail server name.

MX record is an IP address

The MX value must be a hostname, such as mail.example.com. An IP address in that field is not valid and most senders reject it. Create an A record for the mail server and use its name in the MX.

Old MX records left after switching providers

Moving from cPanel hosting to Google Workspace or Microsoft 365 and keeping the old MX records means some mail still goes to the old server, depending on priority. Remove MX records that belong to the previous provider.

Mail server hostname does not resolve

The MX record exists, but its target has no A or AAAA record, so senders have nowhere to connect. This often happens after a server is retired. The IP column here shows it immediately.

How to check MX records

  1. Enter the domain part of the email address, for example example.com for [email protected].
  2. Click Look up MX.
  3. Check that every MX belongs to your current email provider and that each one resolves to an IP address.
  4. Fix any flagged record at your DNS provider, then look again once the old TTL has passed.

What is an MX record?

An MX (mail exchanger) record tells other mail servers where to deliver email for a domain. When someone sends a message to [email protected], their server looks up the MX records for example.com and connects to the server listed there.

Each MX has a priority number. Lower numbers are tried first. If two records share the same priority, senders spread mail between them. Higher numbers act as backups, used when the preferred servers do not answer.

The value must be a hostname that has its own A or AAAA record. It cannot be an IP address and should not be a CNAME. A single MX of "0 .", called a null MX, means the domain does not accept email.

MX records only route incoming mail. Whether your outgoing mail is trusted depends on SPF, DKIM and DMARC, which live in TXT records.

example.com.  3600  IN  MX  1  smtp.google.com.

; Microsoft 365
example.com.  3600  IN  MX  0  example-com.mail.protection.outlook.com.

; Domain that accepts no email (null MX)
example.com.  3600  IN  MX  0  .

When to use an MX lookup

Switching to Google Workspace or Microsoft 365

Confirm the new MX records are live and the old host's records are gone before you tell everyone the move is done.

Email stopped arriving

Check whether the MX records still exist and resolve. A DNS migration that forgot the MX records is a common cause of silent mail loss.

Checking a customer or supplier domain

Before blaming your own server for bounces, look up the recipient domain's MX to see if it accepts mail at all.

Parking a domain

Confirm a null MX is published on domains that should never receive mail, so senders fail fast instead of retrying.

Check something else

Frequently asked questions

What does MX priority mean?

Senders try the lowest number first. Records with equal priority share the load, and higher numbers are fallbacks. The actual numbers do not matter, only their order.

Can a domain receive email without MX records?

Sometimes. Under RFC 5321, if there is no MX, senders try the domain's A or AAAA record instead. Relying on that is fragile, so publish MX records if you want mail, or a null MX if you do not.

Can an MX record point to a CNAME?

It should not. RFC 2181 forbids an MX target from being an alias. Some senders follow it anyway, others reject or defer the mail, so point the MX at a name with its own A record.

How long do MX changes take?

Senders that recently looked up your MX keep the old answer until its TTL expires, often one hour. Mail sent in that window may go to the old server, so keep the old mailbox running for a day after switching.

What are the MX records for Google Workspace?

Google now gives a single record, smtp.google.com with priority 1. Older setups use five records under aspmx.l.google.com and its alternates, which still work.

Why does my MX look right but mail still bounces?

The MX only routes incoming mail. Bounces can come from the receiving server rejecting the address, a full mailbox, or the sender's own SPF, DKIM or DMARC failing. Read the bounce message for the exact reason.

Catch domain outages before your customers do

A broken nameserver or an expired domain takes down your website and your email together. TinyPing checks your site every 5 minutes and alerts you when:

  • the domain stops resolving
  • the site returns an error or times out
  • an expired certificate breaks HTTPS
Start monitoring free for 7 days

US$6.99 a month or US$47 a year per 50 monitors, team members free. 7-day free trial, no card needed.

Want alerts in team chat? Follow the guide for Slack or Google Chat.