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An MX (Mail Exchange) record is a DNS record that specifies the mail server responsible for accepting email on behalf of a domain. MX records are essential for email delivery - without them, other servers cannot determine where to send emails destined for your domain.
Priority value (lower number = higher priority)
Mail server hostname (e.g., mail.example.com)
TTL (Time to Live) - how long DNS servers cache the record
Multiple MX records for redundancy and load balancing
MX records are fundamental to email infrastructure. Without properly configured MX records, your domain cannot receive email. They also play a role in email verification - when validating an email address, verification services check if the domain has valid MX records. Domains without MX records cannot receive email, so addresses on those domains are invalid.
When someone sends an email to user@yourdomain.com, the sending server performs a DNS lookup for your domain's MX records. The MX record returns the hostname of your mail server(s) along with priority values. The sending server then connects to the mail server with the lowest priority number (highest priority) to deliver the message. If that server is unavailable, it tries the next one.
Always have at least two MX records for redundancy
Use different priority values for backup servers
Point MX records to hostnames, not IP addresses
Keep TTL values reasonable (300-3600 seconds)
Ensure mail servers are properly configured to accept mail
Monitor MX records for unauthorized changes
Test MX records after any DNS changes
MX priority determines the order in which mail servers are tried. Lower numbers have higher priority. For example, a server with priority 10 will be tried before one with priority 20. If the primary server (priority 10) is unavailable, mail will be delivered to the backup (priority 20).
You can check MX records using command-line tools like 'nslookup -type=MX domain.com' or 'dig MX domain.com', or use online DNS lookup tools. This shows you which mail servers handle email for that domain.
If a domain has no MX records, some mail servers will fall back to the domain's A record (if it exists) for email delivery. However, this is unreliable and not recommended. Most email verification services will flag addresses on domains without MX records as invalid.
MX record changes typically propagate within 24-48 hours, though they can take up to 72 hours. The actual time depends on your TTL setting and how DNS servers cache your records. During migration, keep old servers running until propagation completes.
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