What Are MX Records For a Domain?

Your MX record will identify which mail servers your domain will accept messages from and the protocol for sorting emails into various folders. Without an MX record properly set up to direct incoming messages, you won’t receive emails.

The Warmup Inbox Team
The Warmup Inbox Team

What Is an MX Record?

A Mail Exchange (MX) record resides in your Domain Name System (DNS)zone file and specifies a mail server to handle your domain’s email. Before you start receiving emails to your domain, you have to set up an MX record.

Your MX record will identify which mail servers your domain will accept messages from and the protocol for sorting emails into various folders. Without an MX record properly set up to direct incoming messages, you won’t receive emails.

MX records consist of two parts: the priority and the domain name. A number measures the priority, and the lower the number, the higher the message’s priority. The domain is the mail server it connects to and will vary based on the company hosting your email. So an MX record could read “0 mail.website.com” and indicate that any messages from website.com are of the highest importance.

Your MX records are maintained through the company where your name servers are pointed. Any changes you want to make to your MX records will have to be done through your email host.

It’s also important to consider where MX records point to. For instance, if a business receives messages directly, the MX record should point to the public IP address of their firewall or Internet-facing email service. Or, if a company uses a hosted cloud service for emails instead, the record should point to the hosting provider’s IP address.

Since deliverability hinges on MX records, it’s crucial to configure the records accurately, especially for businesses that send out mass email campaigns. You can ensure optimum delivery by using the correct MX records, using the correct CNAME records, and keeping your inbox warm

What Is a Backup MX Record?

A backup MX record, or secondary SMTP, filters through incoming messages in the event that your primary server goes offline or fails. Instead of causing emails to bounce, a backup MX record will sort messages to be passed on to the primary server as soon as it’s up and running again.

Backup MXs come with a rudimentary spam filter but are really only beneficial for ensuring that important messages get to the recipient. It’s not meant to act as a secondary measure against malicious content, and if your recipients have backup MX records, it increases your chance of deliverability.

How to Configure Custom MX Records

You would only need to configure custom MX records if you’re switching your email service to a different host and want to have all future emails directed to the new host. Custom MX record configuration points messages to another email provider, and it’s essential to be extremely careful when configuring a custom MX record because if something is out of place, you might stop receiving emails altogether.

Additionally, before you begin configuring a custom MX record, it’s a good idea to back up any emails you want to ensure you save before you start the process.

Start within your current email host’s settings page and go to the Custom MX page. Next to your domain, there should be an “Edit” button, and under “Edit,” you should see “Custom MX Records.”

Then you’ll enter your custom MX record(s) into the fields provided, starting with the priority number and then the domain.

How to Set up an MX Record

Manually setting up your MX record takes place in three steps:

  1. In the TCP/IP settings of your host’s operating system, configure a valid domain name server. This ensures that your operating system will properly resolve domain names and allow you to send and receive emails outside of your locally configured domains.
  2. Configure your MX record on the authoritative name server for your domain. Most of the time, the authoritative name server is the DNS server managed by the company you registered your domain through. Typically, these domain registrars also provide additional services such as DNS hosting. This allows you to utilize a web-based DNS configuration to set up your MX record. Don’t be alarmed if it doesn’t go through right away since most DNS servers temporarily store new information in a cache. It may take up to twenty-four hours for the change to be completely registered in the system. In the meantime, messages can be directed to the secondary email server until the primary server is in effect.
  3. After a day, you can verify that the DNS server accepted the changes by employing an nslookup command-line tool. Once the new record shows up, you’re good to go.

How to Check an MX Record

As stated in the last section, you can use an nslookup command-line tool to identify a domain MX record. However, using commands like this may not be easy, depending on your comfort level with coding.

Thankfully, there are online tools such as MX Toolbox that allow you to generate a comprehensive list of the MX records associated with a domain. The application also helps you identify deliverability problems, run diagnostics, and check your domain against blocklists.