Free MX Record Checker — Verify Mail Exchange DNS Setup

What Are MX Records?

MX (Mail Exchange) records are a type of DNS record that tells the internet which mail servers are responsible for accepting email messages on behalf of your domain. When someone sends an email to your domain, their mail server queries DNS for your MX records to determine where to deliver the message.

Each MX record contains two key pieces of information: a priority value (also called preference) and the hostname of the mail server. The sending server will attempt delivery to the server with the lowest priority number first, and fall back to higher-numbered servers if the primary is unavailable.

Why MX Priority Matters

The priority value in an MX record determines the order in which mail servers are tried during delivery. A lower number means higher priority — a server with priority 10 will be tried before one with priority 20. This system allows you to designate a primary mail server and one or more backup servers.

Correct priority configuration ensures that your primary mail server handles most traffic while backup servers provide a safety net. If two MX records share the same priority, sending servers will distribute load between them randomly, which can be useful for load balancing across multiple servers.

MX Redundancy and Reliability

Having multiple MX records with different priorities provides redundancy for your email infrastructure. If your primary mail server goes down, sending servers will automatically retry delivery using the next server in the priority list. This failover mechanism is built into the SMTP protocol and requires no intervention on your part.

Best practices recommend having at least two MX records pointing to mail servers on different networks or hosting providers. This protects against network outages, hardware failures, and maintenance windows. Without redundancy, a single server failure could cause email to bounce or be delayed for extended periods.

Common MX Record Issues

• Missing MX records — email cannot be delivered to your domain at all
• MX pointing to a CNAME — violates RFC 2181 and can cause delivery failures
• Single MX record — no redundancy if the mail server goes offline
• Unreachable mail servers — MX hosts that do not respond on port 25
• Mismatched priorities — all records at the same priority when failover is intended