StopBouncingUnderstanding MX Record Results
Multiple MX records
A domain with multiple MX records has redundancy built in. The sending server tries the lowest-priority (lowest number) record first, then falls back to higher numbers if unavailable.
Single MX record
A single MX record works fine but offers no redundancy. If that mail server goes down, email delivery will fail temporarily until the server recovers.
No MX records
A domain without MX records cannot receive email. Any email address at that domain is permanently undeliverable — a hard bounce.
Common MX providers
google.com and googlemail.com MX records indicate Google Workspace. outlook.com and protection.outlook.com indicate Microsoft 365. Many others use custom mail servers.
MX Record FAQ
What is an MX record?
An MX (Mail Exchange) record is a DNS record that specifies which mail servers are responsible for receiving 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 where to deliver the message.
Why are MX records important for email deliverability?
If a domain has no MX records, email cannot be delivered to it — any address at that domain will bounce. Email verification services check MX records as one of the first steps to determine if an address is potentially valid.
What does MX priority mean?
MX records include a priority number (lower number = higher priority). If a domain has multiple MX records, the sending server tries the one with the lowest priority number first, then falls back to higher-numbered records if the first is unavailable. This provides redundancy.
What if a domain has no MX records?
If a domain has no MX records, email cannot be delivered to any address at that domain. This is a clear sign that email addresses at that domain are invalid. Some domains fall back to their A record for mail delivery, but this is rare and unreliable.