What are DNS MX records?

Mail Exchange (MX) records are DNS entries that specify the mail servers responsible for accepting incoming email messages on behalf of a domain name, along with preference priorities.

What does MX priority mean?

MX priority is a preference value where lower numbers indicate higher preference. Sending mail servers will attempt delivery to the lowest number first, falling back to higher numbers if unavailable.

How do MX priority numbers work?

MX priority numbers dictate the order in which sending mail servers attempt delivery. The lowest preference number receives the highest priority. For example, a server with priority 10 is attempted before a backup server with priority 20.

Why does my domain need multiple MX records?

Redundancy is critical for email reliability. If your primary mail server is down or undergoing maintenance, sending mail servers automatically route messages to the secondary MX record, preventing bounced emails or delivery failures.

How long do DNS MX record changes take to propagate?

DNS changes typically propagate within minutes to 24 hours depending on the Time To Live (TTL) value configured in your DNS zone file prior to the change.

DNS & Email Routing

MX Lookup Tool

Lookup DNS Mail Exchange (MX) records for any domain. Verify mail server hostnames, priority ordering, IP resolutions, and detected mail service providers.

What is an MX Record?

Mail Exchange (MX) records are essential resource records in the Domain Name System (DNS). Whenever someone sends an email to [email protected], the sending mail transfer agent (MTA) queries the DNS for your domain's MX records to discover where to deliver the email.

Understanding MX Priorities

Every MX record includes a preference or priority integer. Sending mail servers always attempt delivery to the lowest number first.

Primary Mail Host (e.g. Priority 1 or 10)

Receives all standard traffic. If online and responsive, email is accepted immediately.

Secondary / Backup Host (e.g. Priority 20)

Only contacted if the primary server fails to respond, preventing email loss during outages.

Common MX Record Issues

Missing Redundancy: Only one MX host configured. If it goes offline, email bounces.
Pointing to CNAME: MX records must point directly to an A/AAAA hostname, never a CNAME alias (RFC 2181 violation).
Hostname Typo: A misspelled exchange address prevents all incoming mail delivery.

Frequently Asked Questions

Technical specifications, limitations, and SEO recommendations.

A Mail Exchange (MX) record is a DNS record type that specifies which mail server is responsible for accepting incoming email messages on behalf of a domain name.

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