MX Lookup
Look up mail exchange records for any domain. See mail server priorities, IP addresses, and identify the mail provider.
What Are MX Records?
MX (Mail Exchange) records are DNS records that specify which mail servers accept email for a domain. When someone sends an email to user@example.com, the sending server looks up the MX records for example.com to find out where to deliver the message.
How MX Priority Works
Each MX record has a priority value (also called preference). Lower numbers indicate higher priority. When a sending server delivers email, it tries the lowest-priority (highest-preference) server first. If that server is unavailable, it falls back to the next one.
For example, if a domain has MX records with priorities 10 and 20, the server at priority 10 receives all mail first. The server at priority 20 only receives mail when the primary is down.
Common Mail Providers
Our tool automatically detects the mail provider based on MX record hostnames. Common providers include:
- Google Workspace - MX records pointing to
*.google.comor*.googlemail.com - Microsoft 365 - MX records pointing to
*.mail.protection.outlook.com - Zoho Mail - MX records pointing to
*.zoho.com - Proton Mail - MX records pointing to
*.protonmail.ch - Fastmail - MX records pointing to
*.fastmail.com
MX Record Best Practices
- Always have at least two MX records for redundancy.
- Use priority values with gaps (e.g., 10, 20) so you can insert new records later.
- Ensure all MX hostnames resolve to valid IP addresses.
- Never point MX records at IP addresses directly or at CNAME records.
- Keep TTL values reasonable (3600 seconds is common).
Frequently Asked Questions
An MX (Mail Exchange) record is a DNS record that specifies which mail server is responsible for accepting incoming email for a domain. When someone sends an email to your domain, the sender's mail server queries DNS for your MX records to determine where to deliver the message. Without properly configured MX records, your domain cannot receive email.
Use our MX lookup tool by entering any domain name to instantly see all MX records and their priority values. The tool also detects the mail provider (Google Workspace, Microsoft 365, etc.) and resolves IP addresses. Alternatively, use the command line: dig example.com mx on Mac/Linux or nslookup -q=mx example.com on Windows.
MX record priority is a numeric value that determines the order in which mail servers are contacted, where the lowest number indicates the highest priority. If the primary server is unavailable, sending servers automatically try the next server in priority order, providing failover and redundancy for email delivery.
Yes, a domain can and often should have multiple MX records for redundancy and failover. Each MX record points to a different mail server with a different priority value. If two records have the same priority, sending servers randomly distribute email between them, providing load balancing.
MX records are specifically for email routing and tell sending servers which server handles email for a domain. A records map a domain name to an IP address for general DNS resolution. An MX record's hostname must itself have an A record so sending servers can resolve it to an IP address for connection.
MX record changes typically propagate globally within 24 to 48 hours, though some resolvers may take up to 72 hours. The actual time depends on the TTL value of your previous records and DNS resolver caching behavior. Use online propagation checkers to monitor status across different regions.
Common causes include DNS propagation delay (up to 48-72 hours), typos in the mail server hostname, incorrect priority values, or old conflicting MX records that were not removed. Verify your records match your email provider's specifications, and check that the mail server hostname has a valid A record pointing to the correct IP.
If a domain has no MX records, most sending servers will fall back to the domain's A record and attempt delivery there, per RFC 5321. However, this fallback is unreliable and not recommended. Missing MX records signal poor domain configuration, which can negatively affect sender reputation and deliverability.