What is an MX Record

These days most organizations own a domain and have a presence on the web. An integral part of a business’s online presence is communication. While there are many ways of communicating online, email is still one of the most used methods. And like anything else in DNS, domain-based emails need a record. This record is the Mail Exchange (MX) record, and in this resource, you’ll learn all about it.

MX Records Explained

The main purpose of an MX record is to instruct servers on where to deliver emails. This is done via the Simple Mail Transfer Protocol (SMTP). It’s an MX record that provides nameservers with the location of your domain “mailbox.” For this record type to function correctly, it must point to an A or AAAA record.

Tip: MX Records can never point to a CNAME record.

MX Record Example

Here are some examples of an MX record configuration.

Now let’s take a look at how an MX record would look in DNS Made Easy. The main MX fields will be similar for all providers, but names may vary. GTD is DNS Made Easy’s exclusive Global Traffic Director feature.

MX Record Levels (Priority)

MX records have a unique feature that allows you to set the level of mail servers in your configuration. The level specifies which mail server should be used first. The lower the level, the higher the priority. It’s recommended to have multiple MX records to avoid disruption in your domain’s email services. While MX records don’t support Failover, prioritizing mail servers by level achieves the same result. You can also have several MX records with the same level, like a round robin configuration. When set up like this, servers will balance the load between email servers equally, and at random.

Tip: Priorities are typically set in increments of 5 or 10. This is mostly for convenience or to allow for future adjustments. MX priorities can also start at 0 and just be single digits, or even 53 or 102. It really boils down to your organization’s preferences. The important thing to remember is to assign the lowest value to the most preferred server.

DNS Lookup for MX Records

After configuring your MX records, it’s always a good idea to verify that they are behaving as expected. You can do this by using a command line utility in Windows, Mac, or Linux. You can also use a free online resource like Constellix’s DNS Lookup Tool. This lets you retrieve DNS records and run checks based on geographic location. It will also query against any nameserver you specify.  

MX Record Summary

Now that you know what MX records are, configuring them will be easy. It’s recommended to have at least two mail servers to avoid disruptions with your email services. How you prioritize your mail servers will depend on your domain’s specific needs. You can base levels on preference, or assign the mail servers the same level to cycle traffic equally between them. You also want to make sure your MX records point to an A or AAAA record. If you’re a current DNS Made Easy customer or just want to learn more, visit our MX Record tutorial.

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If you liked this, you might find these helpful:

MX Records

RFC 2181 10.3

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