DNS & Email

What is an MX record, and why does your email depend on it?

Inboxlogy6 min readUpdated 2026-10-26

In short: An MX (Mail Exchange) record tells the internet which servers receive email for your domain, and in what order to try them. The lowest priority number is tried first. Without a valid MX record, your domain simply cannot receive mail. The MX record also reveals which provider (Google, Microsoft and so on) runs a domain's email.

On this page

  1. What does an MX record actually do?
  2. How does MX priority work?
  3. What can an MX lookup tell you?
  4. What goes wrong with MX records?

What does an MX record actually do?

An MX record is a DNS entry that points your domain to its inbound mail servers. When someone sends you an email, their server looks up your domain's MX records to find out where to deliver it. Each MX record has two parts: a priority number and a hostname (the mail server). It's the postal address for your domain's inbox.

Key point: MX records control incoming mail. They do not control who can send as your domain. That job belongs to SPF, DKIM and DMARC. Many deliverability problems come from confusing the two.

How does MX priority work?

A domain can list several MX records for redundancy. The lower the priority number, the higher the preference, so a record with priority 10 is tried before one with priority 20. If the primary server is unreachable, the sender falls back to the next. Equal priority numbers share the load. For example, Google Workspace typically publishes a single smtp.google.com MX; Microsoft 365 publishes a …mail.protection.outlook.com host.

What can an MX lookup tell you?

Beyond confirming a domain can receive mail, an MX lookup reveals the email provider behind a domain. If the MX points to google.com, it's Google Workspace; outlook.com or protection.outlook.com means Microsoft 365; others point to Zoho, Proofpoint, Mimecast and so on. This is handy for sales research, deliverability debugging, and verifying that a newly configured domain is pointed at the right provider.

What goes wrong with MX records?

The most common issues are: no MX record at all (the domain can't receive mail), MX pointing to a decommissioned server (mail bounces), a typo in the hostname, or an MX pointing to an IP address instead of a hostname, which is invalid because MX records must point to a name, not an IP. A quick MX lookup surfaces all of these.

Find any domain's mail servers, free

Look up MX records in priority order and auto-detect the email provider (Google, Microsoft, Zoho and more).

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Frequently asked questions

What happens if a domain has no MX record?
Without an MX record, mail servers have no instructions on where to deliver email for that domain, so incoming mail fails or bounces. Some senders fall back to the domain's A record, but that is unreliable, so every mail-receiving domain should have valid MX records.
What does the MX priority number mean?
The priority number sets the order servers are tried. Lower numbers are preferred and tried first. A record with priority 10 is used before one with priority 20. Multiple records with the same priority share incoming mail between them.
Can I tell what email provider a company uses?
Yes. A domain's MX records reveal its email provider: Google Workspace points to google.com hosts, Microsoft 365 to protection.outlook.com, and so on. An MX Lookup tool detects and labels the provider automatically.
Do MX records affect whether my email lands in spam?
Indirectly. MX records govern receiving, not sending. Still, a misconfigured domain signals a sloppy setup. Your sending reputation depends mostly on SPF, DKIM, DMARC and IP reputation, not MX.

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