Understanding DNS MX Records: The Key to Secure Email Communication

DNS (Domain Name System) is the backbone of the internet that connects website addresses to their actual IP addresses. One of the essential types of DNS records is the MX record, which stands for Mail Exchange record. MX records determine the mail servers that handle email deliveries for a specific domain.

In this article, we will dive deep into the world of MX records, how they work, and why they are crucial for any domain that wants to receive and send emails.

What are MX Records?

MX records are a type of DNS record that provides information about the mail servers that handle the email delivery for a specific domain. These records are used by email servers to determine the correct destination for email delivery.

When an email is sent to a domain, the recipient’s mail server performs a DNS lookup to retrieve the MX record for that domain. The mail server then uses the information contained in the MX record to route the email to the correct mail server for delivery.

Why are MX Records Important?

MX records are used to identify the mail servers that are authorized to handle email communications for a specific domain. The records provide the necessary information to direct incoming emails to the right server, ensuring that they reach their intended recipients.

MX records play a crucial role in ensuring that emails are delivered to the correct recipient. Without MX records, email servers would not know where to deliver email messages, leading to undeliverable emails and lost communication.

In addition, MX records can also be used to set priority levels for mail servers. This means that if one mail server is down, the email can be delivered to another mail server with a lower priority.

Having accurate and up-to-date MX records is essential for the smooth functioning of email communications. Incorrect or outdated MX records can lead to emails being lost or delivered to the wrong inbox, resulting in missed opportunities and potential damage to your online reputation.

person using smartphone and laptop computer

How MX Records Work

MX records work by using a priority system. Each MX record is assigned a priority number, with the lower numbers indicating a higher priority. Incoming emails will be directed to the mail server with the lowest priority number first. If that server is unavailable, the email will be redirected to the next available server with the next lowest priority number. This redundancy ensures that emails are delivered even if one of the servers is down.

Setting up MX Records

Setting up MX records requires access to your domain’s DNS configuration. This can usually be done through your domain registrar or hosting provider. To set up MX records, you need to specify the hostname of your mail server and assign a priority number.

It is important to note that it can take up to 72 hours for changes to MX records to take effect. This is because of the way that DNS information is propagated throughout the internet.

How to Configure MX Records

MX records are usually managed by the domain registrar or hosting provider. To configure MX records, you need to log into your domain registrar account or hosting account and modify the DNS settings.

It is essential to note that MX records should be configured correctly to ensure that email deliveries are successful. Incorrectly configured MX records can lead to email delivery problems, including undeliverable emails and email delays.

MX Record Examples

Here is an example of MX records to give you an idea of what they look like:

mutantmail.com MX 10 mail.mutantmail.com
mutantmail.com MX 20 backup.mail.mutantmail.com

In this example, the first MX record has a priority of 10, and the second MX record has a priority of 20. The mail server mail.mutantmail.com will handle email deliveries for the mutantmail.com domain, and if it is down, the email will be delivered to backup.mail.mutantmail.com.

Common MX Record Issues

There are several common issues that can arise with MX records, including:

  • Incorrect priority numbers, leading to emails being directed to the wrong server
  • Missing MX records, resulting in emails being rejected or lost
  • Outdated MX records, which can cause emails to be misdirected
  • Duplicate MX records, which can cause confusion and potential email delivery problems

To avoid these issues, it is important to regularly check and update your MX records to ensure that they are accurate and up-to-date.


MX records are a crucial component of the DNS system, ensuring that emails are delivered to the correct recipient. They provide important information about the mail servers that handle email deliveries for a specific domain.

To ensure successful email deliveries, it is essential to configure MX records correctly and regularly monitor their performance. With a solid understanding of MX records, you can keep your email communication running smoothly and efficiently.

Did you know, at Mutant Mail we have a zero downtime infra setup using multiple MX records?