What Is an MX Record?

Acutis · plain-English network help · updated June 2026

What is an MX record, in plain English?

An MX record (short for "Mail eXchange" record) is a DNS entry that tells the rest of the internet where to deliver email for your domain. When someone sends a message to you@example.com, their mail server looks up the MX record for example.com to find out which server is allowed to receive that mail. Without an MX record, other servers simply have nowhere to hand the message off, and delivery fails.

Think of it as the mailing address for your domain's inbox. Your domain name is the household name; the MX record is the actual street address that the postal service uses to deliver the letter. The two are related but separate, which is why your website and your email can live on completely different servers.

How mail routing actually works

When you hit send, your message does not fly straight to the recipient's inbox. It travels through a short chain of lookups, much like a DNS lookup for a website:

1. The sending server reads the address. It takes the part after the @ sign — the domain — and prepares to ask DNS about it.
2. It queries the domain's MX records. DNS returns one or more mail servers, each with a hostname and a priority number.
3. It picks the highest-priority server. The sending server connects to the preferred mail host and attempts delivery.
4. The receiving server takes over. That host accepts the message, runs its spam and authentication checks, and drops it into the right mailbox.

All of this happens in seconds. The MX record is the signpost that makes step two possible — change it, and email for the whole domain starts flowing somewhere new.

MX priority: lower number wins

Every MX record carries a priority value, and this trips a lot of people up because the logic is reversed from what you might expect. A lower number means higher priority. So a server with priority 10 is tried before one with priority 20.

• Lower number = first choice. The mail server with the smallest priority value receives mail under normal conditions.
• Higher numbers = backups. If the primary server is unreachable, the sender falls back to the next-lowest priority — your secondary or "failover" mail host.
• Equal numbers = load balancing. If two MX records share the same priority, mail is spread roughly evenly between them, which is how big providers distribute incoming volume across many servers.

A typical record set looks like 10 mx1.example.com and 20 mx2.example.com — primary and backup. Google Workspace and Microsoft 365 publish several records at equal priority so no single inbound server is overloaded.

What "no MX record" means

If a domain has no MX record at all, it usually means one of a few things, and none of them are subtle once you know to look:

• The domain does not receive email. Plenty of domains are used only for a website or for redirects and were never set up to accept mail.
• Email is misconfigured. The owner intended to receive mail but never added (or accidentally deleted) the MX record, so legitimate messages bounce back to senders.
• A fallback to the A record. By an old rule, if no MX exists, some senders will try the domain's plain address (its A record) directly. This rarely works on modern setups and should not be relied on.

If your inbound mail suddenly stops, a missing or wrong MX record is one of the first things worth checking.

Common providers behind MX records

You can usually tell who runs a domain's email just by reading its MX hostnames. A few you will see constantly:

• Google Workspace: hostnames ending in google.com or googlemail.com (modern setups often use a single smtp.google.com record).
• Microsoft 365: a record like example-com.mail.protection.outlook.com.
• Proton Mail: hostnames under protonmail.ch.
• Zoho, Fastmail, and others: each publishes its own clearly branded mail hosts.

If the MX points at your hosting company's generic mail server, that is a hint your email and website share one provider — fine for small setups, but most businesses move email to a dedicated platform for reliability and better spam protection.

Where MX records fit in the bigger picture

An MX record gets mail to the right server, but it says nothing about whether that mail is trusted. That job belongs to a trio of other records — SPF, DKIM and DMARC — which prove the message is genuinely from you and not a forgery. A domain with a perfect MX record can still see its outbound email land in spam if those authentication records are missing or broken. The MX is the address; the authentication records are the signature.