If email sent to your domain is bouncing, disappearing, or never arriving, there's a good chance the culprit is a small but critical DNS setting: your MX records. They're the part of your domain's configuration that decides where incoming email is delivered — and when they're wrong, mail simply has nowhere to go. Here's what MX records are, how they route email, how to check yours in seconds, and how to fix the most common problems.

What are MX records?

MX stands for Mail Exchange. An MX record is a type of DNS record that tells the rest of the internet which server is responsible for receiving email for your domain. Just as an A record points your domain's website to a server, an MX record points your domain's email to a mail server.

When someone sends a message to you@example.com, their mail server doesn't magically know where to deliver it. It performs a DNS lookup for example.com's MX record, finds the address of your mail server, and hands the message over. No MX record — or a wrong one — and that delivery fails. (For the bigger picture of how DNS lookups work, see our guide on what a DNS lookup is.)

How MX records route email (and what priority means)

A domain can have more than one MX record, and each carries a priority value — a number that sets the order in which mail servers should be tried. The key rule catches people out: a lower number means higher priority. So an MX record with priority 10 is tried before one with priority 20.

This lets you set up a backup. Mail always goes to the lowest-numbered (highest-priority) server first; if that server is unavailable, the sending server falls back to the next one in line. Many domains have a primary and one or two backups configured this way for reliability.

A couple of technical rules matter here:

  • An MX record must point to a hostname (like mail.example.com), never directly to an IP address.
  • That hostname must not be a CNAME (alias) — it needs to resolve to a real A or AAAA record. Pointing an MX at a CNAME is a common misconfiguration that breaks delivery.

How to check your MX records

You can view any domain's MX records in seconds — they're public. The easiest way is a free online lookup: enter your domain into our DNS Records tool and it returns your MX records (along with every other record type) instantly, so you can confirm they point to the right mail server with the right priority. Our guide on how to look up DNS records for any domain covers reading the full results.

If you prefer the command line, you can query MX records directly:

nslookup -type=MX example.com
dig example.com MX +short

Swap example.com for your domain. Either way, you're looking for records that point to your intended mail provider (for example, your hosting or email service's mail servers) with sensible priority values.

Common MX problems and how to fix them

Most email-routing failures trace back to one of these:

  • No MX record at all. If your domain has no MX record, incoming mail bounces immediately. The fix is to add the MX record(s) your email provider specifies.
  • MX points to the wrong or old server. After switching email providers, an MX still pointing at the old host sends mail to a mailbox no one checks. Update it to your new provider's mail servers.
  • Wrong priority order. If a backup server is accidentally set as the primary, mail may route to the wrong place. Confirm the main server has the lowest number.
  • MX pointing to a CNAME or an IP. As noted above, this breaks delivery. Point the MX to a proper hostname that has its own A/AAAA record.
  • Recent change hasn't propagated. DNS changes take time to spread, and your device may show a cached old value. Give it time, and flush your DNS cache to see the current records.

After any change, re-check with the DNS tool to confirm the new records are live before assuming the problem is fixed.

MX records vs SPF, DKIM and DMARC

Here's a distinction that trips people up: MX records decide where email is delivered, but they don't decide whether your outgoing email is trusted. That job belongs to TXT records — specifically SPF, DKIM and DMARC — which authenticate your mail so it doesn't land in spam. So if your incoming mail arrives fine but your outgoing mail keeps getting flagged as spam, the problem isn't your MX records; it's your TXT authentication records. Both live in your DNS settings, and both are worth checking when email misbehaves.

The bottom line

MX records are the signposts that route incoming email to the right mail server, with priority values setting the order servers are tried — remember, lower numbers win. When email won't arrive, checking your MX records is the first move: confirm they exist, point to the correct hostname, and carry the right priorities. Use a free DNS Records lookup to see them instantly, fix any that are missing or misdirected, and give the change time to propagate. Get the MX records right, and your email routing falls neatly into place.