MX Lookup
What Is an MX Lookup?
An MX (Mail Exchange) lookup queries the DNS for the mail server records associated with a domain. MX records are essential for email delivery - they tell sending mail servers which servers are responsible for receiving email for a given domain. Without properly configured MX records, email sent to addresses at your domain will not be delivered.
Each MX record contains two key pieces of information: a priority value and a mail server hostname. The priority value (sometimes called preference) determines the order in which mail servers are contacted. A sending server first attempts delivery to the mail server with the lowest priority number. If that server is unavailable, it tries the next server in priority order, providing built-in redundancy for email delivery.
Our MX lookup tool queries Cloudflare's DNS infrastructure to retrieve all MX records for a domain, resolves each mail server hostname to its IP address, and presents the results sorted by priority. This gives you a complete picture of how email is routed for any domain.
MX records are commonly used to identify which email service provider a domain uses. For example, domains using Google Workspace typically have MX records pointing to aspmx.l.google.com, while Microsoft 365 domains point to mail.protection.outlook.com. This information is valuable when troubleshooting email delivery issues, migrating between email providers, or verifying that DNS changes have propagated correctly.
Understanding MX records is particularly important for email deliverability. Misconfigured MX records can cause email to bounce, be delayed, or be routed to the wrong server. Combined with SPF, DKIM, and DMARC records, MX records form the foundation of a domain's email infrastructure. Our related tools can help you verify the complete email authentication chain for any domain.
Frequently Asked Questions
What is an MX record?
An MX (Mail Exchange) record is a DNS record that specifies which mail servers are responsible for accepting email for a domain. Each MX record contains a priority value and a hostname. Email is routed to the server with the lowest priority number first, with higher-priority servers used as fallbacks.
What does MX priority mean?
MX priority (also called preference) is a numeric value that determines the order in which mail servers are tried. Lower numbers indicate higher priority. If the primary server is unavailable, email is delivered to the next server in order. Multiple servers with the same priority receive email in a round-robin fashion.
Why does my domain have no MX records?
If your domain has no MX records, email servers will fall back to the domain's A record for mail delivery. However, this is unreliable and not recommended. To receive email, you should configure MX records pointing to your email provider's mail servers.
How do I check which email provider a domain uses?
Performing an MX lookup reveals the mail servers handling email for a domain. Common patterns include aspmx.l.google.com for Google Workspace, mail.protection.outlook.com for Microsoft 365, and mx.zoho.com for Zoho Mail.