MX Record Checker

An MX (Mail eXchange) record is a DNS record that tells other mail servers where to deliver email for a domain. Each MX record points to a host name and carries a priority number: when a message is sent, the sending server tries the mail server with the lowest priority value first and falls back to the next one if it is unavailable.

Without a valid MX record, messages addressed to the domain cannot be delivered and will bounce. MX records are the foundation of email reception, which is why every domain that receives mail needs at least one.

• Enter a domain name, an email address or a URL — we extract the domain automatically.
• We query the domain’s MX records in public DNS and sort them by priority, lowest first.
• Each mail server is resolved to its IPv4 and IPv6 addresses so you can confirm it actually points somewhere.
• We flag common problems: no MX, a null MX, an MX pointing to an IP address, duplicate priorities, a single point of failure and servers that do not resolve.

The priority (also called preference) is a number from 0 to 65535. Lower values are preferred, so an MX with priority 10 is tried before one with priority 20. A domain usually lists several mail servers so that mail still arrives if the primary one is down.

When two MX records share the same priority, sending servers pick between them at random, which spreads the load evenly. Different priorities create a clear primary-and-backup order instead.

• No MX records — mail cannot be delivered at all. Some servers fall back to the A record, but you should never rely on that.
• MX pointing to an IP — an MX record must contain a host name such as mail.example.com, not an IP address.
• A single mail server — if it goes offline, incoming mail is lost or delayed. Add at least one backup MX.
• An unresolved mail server — the host in the MX record has no A or AAAA record, so no one can connect to it.
• Null MX — a single record with the target “.” means the domain intentionally accepts no mail — correct for send-only or parked domains.

MX records decide where mail is delivered, but authentication decides whether it is trusted. After confirming your mail servers, validate SPF, DKIM and DMARC with our other checkers, then send a test message to a temporary TempBox address to see the full picture.