MX Lookup

Look up mail exchange (MX) records for any domain.

Enter Domain Name

What are MX Records? Mail Exchange (MX) records are DNS entries that specify mail servers responsible for accepting email messages on behalf of a domain. Each record has a priority value (lower number = higher priority) that determines the order in which mail servers are used. When sending email, the sending server will first try the mail server with the lowest number (highest priority).

MX Lookup Guide

What are MX Records?

Mail Exchange (MX) records are specific DNS records that identify the mail servers responsible for receiving email on behalf of a domain. They are a fundamental part of the email delivery system on the internet. When you send an email to someone@example.com, the sending mail server looks up the MX records for example.com to determine which mail server should receive the message.

Each MX record contains two key pieces of information: a priority value (also called preference) and a mail server hostname. The priority value determines the order in which mail servers should be contacted, with lower numbers indicating higher priority. This system allows for backup mail servers that will accept mail if the primary server is unavailable.

How Do MX Records Work?

MX records work through these steps in the email delivery process:

Email Composition: A user sends an email to recipient@example.com.
MX Record Lookup: The sending mail server performs a DNS query for MX records associated with example.com.
Priority Sorting: The mail server sorts the returned MX records by priority value (lowest number first).
Connection Attempt: The mail server attempts to connect to the highest priority mail server in the list.
Failover Process: If the connection fails, the sending server tries the next mail server in the priority list.
Email Delivery: Once connected, the sending server delivers the email to the receiving mail server.

How to Perform an MX Lookup

There are several methods to check MX records for a domain:

Using our tool: Enter the domain name in the field above and click the "Lookup MX Records" button.
Command line (Windows): Open Command Prompt and type nslookup -type=MX example.com
Command line (Linux/macOS): Open Terminal and type dig MX example.comor host -t MX example.com
Online tools: Various online DNS lookup services can check MX records for any domain.
Programming APIs: DNS libraries in most programming languages can query MX records programmatically.

Applications of MX Records Lookups

Email System Setup

System administrators use MX lookups when configuring email systems to ensure proper delivery.

Email Service Verification

Verifying that email services are correctly configured before launching websites or services.

Email Delivery Troubleshooting

Diagnosing email delivery issues by checking if MX records are properly set up.

Email Provider Identification

Determining which email service a domain is using based on its MX records.

Spam Prevention

Email security systems verify MX records as part of sender validation procedures.

Email Migration Planning

Planning email system migrations requires understanding current MX configurations.

Benefits and Limitations of MX Lookup

Benefits:

Provides clear visibility into a domain's email infrastructure
Helps troubleshoot email delivery issues quickly
Allows for verification of email server configuration
Supports email system redundancy through priority-based failover
Enables identification of email service providers being used

Limitations:

MX records alone don't guarantee email delivery or security
DNS propagation means changes to MX records can take time to take effect
MX lookups don't verify if mail servers are properly secured
The presence of MX records doesn't confirm that email authentication (SPF, DKIM, DMARC) is configured
MX records may be misconfigured but still visible in lookups

Technical Considerations

When working with MX records, keep these technical details in mind:

DNS TTL (Time To Live): MX records have a TTL value that determines how long DNS resolvers should cache the information. When changing MX records, you may need to wait for this period to expire before changes take effect globally.
Mail Server Redundancy: Best practices suggest having at least two MX records with different priority values to ensure email delivery even if one server fails.
A Records Requirement: The hostname specified in an MX record must have a corresponding A or AAAA record (not another MX record).
Special Case - Null MX: A domain that doesn't accept email should use an RFC 7505 'null MX' record (priority 0, target '.') rather than having no MX records.