---
title: "MX records explained"
description: "MX records tell the world where to deliver your email. How priority works, how to set up a backup server, and the mistakes that make mail bounce."
canonical_url: "https://dnsense.io/learn/mx-records-explained"
---

> Index of every page on this site: [llms.txt](https://dnsense.io/llms.txt)

An MX record names the server that accepts email for a domain. Without one, mail to `you@example.com` has nowhere to go. A wrong one sends it to a stranger.

## Priority decides the order

Every MX record has a priority number and a target hostname. The sender tries the **lowest** number first. If that server does not answer, it moves on to the next.

![A sender trying mail1.example.com with priority 10 first and mail2.example.com with priority 20 as backup](guide-records-mx.webp)

Two records with the same priority share the traffic. Different priorities give you a primary and a fallback. The numbers themselves mean nothing. Only their order does, so 10 and 20 work as well as 1 and 2.

## Rules for the target

- It must be a **hostname**, not an IP address. DNSense says so when you paste an address.
- That hostname needs its own A or AAAA record.
- It must not be a CNAME. Some mail servers follow the alias, others bounce the message.

## Hosted mail

Google Workspace, Microsoft 365 and other mail providers give you a set of MX records to copy. Remove the old ones when you switch. A leftover MX record at a higher number is still a valid destination, and some mail will keep arriving at the old provider.

## If a domain sends no mail

Say so with a null MX: priority 0, target `.`. Senders then fail immediately instead of retrying for days. DNSense checks MX targets as hostnames, so set a null MX at your provider if it supports one.

## Adding one in DNSense

Click **Create record**, choose **MX**, leave the name empty for the root domain, and fill in the **Mail server** and the **Priority**. Google Workspace has its own quick fill. Set the TTL to 3600 or lower while you test.

![The New record dialog with an MX record, mail server and priority](app-records-mx-form.webp)

In the table the priority shows in the Extras column. Lowest wins.

![The zone filtered on MX records, with priorities 10 and 20](app-records-mx-list.webp)

## After you change it

Send a test message from an outside address and check the headers, or use the MX lookup in the record menu. Mail uses its own retry rules, so a typo can take hours to show up as bounces. Test before you leave.

## Sitemap

See the full [sitemap](https://dnsense.io/sitemap.md) for all pages.