What is an MX (Mail Exchanger) record?

Still have a question, spotted an error, or have a better explanation or a source we should cite?

Someone sends an email to captain@deepcurrent.io. Their mail server needs to figure out where to deliver it. So it asks DNS a simple question: "Where does mail for deepcurrent.io go?" The answer comes back from one record: the MX record.

An MX record (Mail Exchanger record) is a DNS entry that points to the mail server responsible for receiving email on behalf of your domain. No MX record means no way to receive mail. It's that direct.

Every MX record has two parts. The host is the address of the mail server itself (something like aspmx.l.google.com for Google Workspace, or mail.protection.outlook.com for Microsoft 365). The priority number tells sending servers which one to try first. Lower number gets first priority.

A real-world example looks like this:

deepcurrent.io MX 10 mail1.deepcurrent.io
deepercurrent.io MX 20 backup.deepcurrent.io

Still if the priority 10 server is unreachable, the sending server tries priority 20. That's your fallback. You can learn more about how priority levels work and what fallback servers actually do in the next few questions.

One thing that surprises people: MX records control inbound mail, not outbound. Your SPF, DKIM, and DMARC records handle the sending side. But here's the catch: some receiving servers will quietly check whether your domain even has a valid MX record before accepting mail from you. A missing or broken MX record can make your domain look suspicious, even if you're only trying to send.

If you're setting this up for the first time, your email provider (Google Workspace, Microsoft 365, Zoho Mail, your hosting company) will give you the exact values to add. You add them in your DNS settings, usually at your domain registrar or DNS provider. Changes can take up to 48 hours to propagate, though in practice it's often much faster.

Not sure if your MX record is set up correctly? You can check it right now with our free Email Header Analyzer, or just reach out via the SOS hotline if something's not working and you want a second pair of eyes.

Contributors

Who worked on this answer

Every name links to their profile. Every company links to their site. Real people, real accountability.

Yanna-Torry (YT) Aspraki

Founder · Author

Review My Emails

Ask an AI · tailored to your setup

Check my MX record setup

I just read about MX records on the Email Almanac and want to check or fix mine. Here's my situation: - Domain I'm setting up email for: e.g. mycompany.com - Email provider: [e.g. Google Workspace, Microsoft 365, Zoho, custom mail server] - Domain registrar or DNS provider: e.g. GoDaddy, Cloudflare, Namecheap - What I see in my DNS right now (if anything): paste MX record values if you have them - What's actually broken or unclear: [e.g. not receiving mail, not sure if values are correct, setting up for first time] - Any error messages: paste if you have one Based on this, can you: 1. Tell me if my MX record looks correct for my provider 2. Flag anything that looks misconfigured or missing 3. Walk me through what to change and where 4. Tell me how long propagation should take and how to verify it worked

Edit the yellow boxes, then send to the AI of your choice.