MX Records ​

MX records, or Mail Exchange records, play a crucial role in email delivery. They ensure that incoming emails reach the correct destination. If your MX records are misconfigured, your domain won't receive emails, no matter the provider. These records operate in the background for all domains, whether you use Gmail, Outlook, or a custom mail server.

What is an MX Record? ​

An MX record is a special type of DNS (Domain Name System) record that tells the world which mail servers should receive email for your domain. Think of it as your domain's digital mailing address. When someone sends a message to you@example.com, the MX record ensures that the message is routed to the correct server.

Each MX record points to a mail server, identified by its hostname, and includes a priority value. The lower the number, the higher the priority. This system allows for a backup server, if the primary server is down, the next one in line will handle the email. For example, a business might have mail1.example.com as its main server (priority 10) and mail2.example.com as a backup (priority 20).

Here's what a typical MX record looks like in DNS:

example.com.  3600  IN  MX  10  mail1.example.com.
example.com.  3600  IN  MX  20  mail2.example.com.

How Do MX Records Work? ​

When someone sends an email to your domain, the process begins with the sender's mail server querying DNS for your MX records. The DNS response lists one or more MX records, each with a priority number and a mail server hostname. The sending server always tries to deliver the message to the server with the lowest priority number first. If that server is unavailable, it moves on to the next one in order. This fallback mechanism ensures that email delivery is resilient, even if a server goes offline.

In high-volume environments, organizations often use multiple servers with the same priority. This allows sending servers to randomly select one for each delivery attempt, balancing the load across several machines and improving reliability.

Most businesses today use third-party email providers, which require specific MX configurations. For example, a Google Workspace setup might use several MX records with different priorities, while Microsoft 365 or Amazon WorkMail will have their own unique configurations. No matter the provider, the principle is the same: MX records guide every incoming email to its proper destination.

Why are MX Records Important? ​

MX records are absolutely essential for receiving email. Without them, your domain is essentially unreachable. Most mail servers will refuse to deliver messages to a domain that lacks MX records. Even though the SMTP standard allows fallback to the domain's A record, modern servers rarely do this for security reasons.

Beyond basic delivery, MX records play a role in your domain's reputation and deliverability. Spam filters often check that your MX records align with your other DNS settings, such as SPF and DKIM, to confirm your domain's legitimacy. If your MX records are missing or misconfigured, you risk having emails bounce or be marked as spam. When switching email providers, updating your MX records is what actually moves your email flow. A single typo can cause lost messages or downtime, so accuracy is critical.

Frequently Asked Questions About MX Records ​

What happens if my domain has no MX records? ​

If your domain has no MX records, most mail servers will not deliver email to it, even though technically they could try the domain's A record. In practice, no MX means no email delivery. This makes MX records mandatory for any domain that needs to receive email.

How long do MX record changes take to update? ​

Changes to MX records depend on the TTL (Time To Live) value set in your DNS. Most updates take from a few minutes up to 48 hours to fully propagate worldwide. For planned migrations, it's smart to lower your TTL a day or two in advance.

Can I use MX records from different providers at the same time? ​

You can, but it's only recommended for advanced setups like migrations or split delivery. Both providers must be configured to know which mailboxes they handle, or you risk losing emails. For most organizations, sticking to one provider is simpler and safer.

Related Content ​

• SMTP (Simple Mail Transfer Protocol)
• SPF (Sender Policy Framework)
• DKIM (DomainKeys Identified Mail)
• DMARC (Domain-based Message Authentication, Reporting & Conformance)
• Email Authentication
• Return Path
• CNAME Records