MX Record (Mail Exchange Record)

What Is an MX Record?

An MX record (Mail Exchange record) is a DNS record type that specifies which mail servers are responsible for accepting incoming email for a domain. When someone sends an email to [email protected], the sending mail server looks up the MX records for company.com to find where to deliver the message. Without MX records, a domain cannot receive email — any address at that domain is effectively invalid, regardless of how syntactically correct it looks.

MX Record Structure

An MX record has two key components: a priority value (a number — lower number means higher priority) and the hostname of the mail server. For example, a domain might have two MX records: MX 10 mail1.company.com and MX 20 mail2.company.com. The sending server tries the priority 10 server first. If it's unavailable, it falls back to the priority 20 server. Multiple MX records with different priorities provide redundancy — if the primary mail server is down, email is queued and delivered to the backup.

MX Records in Email Verification

Checking MX records is one of the first steps in EmailVerify.io's verification pipeline. If a domain has no MX records, there's no mail server to receive email — the address is invalid. If MX records exist but point to non-functional servers, that's a different problem but equally undeliverable. MX record validation is fast, reliable, and eliminates an entire category of invalid addresses before attempting the slower SMTP handshake check. It's one of the most cost-effective filters in the verification chain.

MX Records and Domain Health

A domain's MX configuration is a signal of its operational status. Domains with properly configured, actively maintained MX records that respond to SMTP connections are likely to have real users. Domains whose MX records point to non-existent servers, or whose MX records have recently been removed, are likely abandoned or deactivated. Email addresses at these domains generate hard bounces. MX record health monitoring is valuable for any business managing large contact databases.

Common MX Record Issues

MX records pointing to a domain rather than a hostname (the target of an MX record must be an A record, not a CNAME — this is a common misconfiguration). MX records with incorrect syntax or missing the trailing period. Out-of-date MX records after migrating to a new email provider. MX records that exist but whose target servers are unreachable. Each of these causes email delivery problems and verification failures. EmailVerify.io's verification detects MX-level issues as part of its domain validation. Check your email deliverability setup at emailverify.io.

MX Records vs. A Records for Email

A records map domain names to IP addresses. MX records point to the hostname of a mail server — which itself must have an A record. The two-step lookup (domain → MX record → A record → IP) is by design: it allows a single domain to use different servers for web traffic and email traffic. Your website might be hosted on one server while your email is handled by Google Workspace on entirely different servers. MX records make this separation possible.