Free MX record lookup tool. Check the MX records for any domain: priority-ordered mail hosts, each resolved to its IPv4 and IPv6 addresses with reverse DNS, the detected mail provider (Google Workspace, Microsoft 365, Zoho, and more), and health checks that flag missing MX records, CNAME targets, null MX (RFC 7505), unresolvable hosts, and single points of failure. Runs from our London probe. Useful for email deliverability troubleshooting, mail migrations, and verifying MX changes.
An MX (Mail Exchange) record tells the rest of the internet where to deliver email for your domain. Each record pairs a mail host with a priority number, and a sending server tries the lowest priority first, falling back to higher numbers if that host is unreachable. A lookup for gmail.com returns several hosts at different priorities, which is how large providers spread inbound load and stay resilient. This tool resolves each MX host to its IPv4 and IPv6 addresses, adds reverse DNS, and names the detected provider so you can confirm mail is pointed where you expect.
A few MX mistakes silently drop or delay mail. An MX record must point at a hostname with real address records, never at an IP and never at a CNAME, which several RFCs forbid and some senders reject outright. Having only one MX host is a single point of failure: if it goes down, mail bounces or queues instead of rolling over. A special case is the null MX (a single . at priority 0, per RFC 7505), which correctly declares a domain sends no mail and should receive none. This tool flags missing records, CNAME targets, unresolvable hosts, and single points of failure.
An MX (Mail Exchange) record is a DNS record that names the mail server responsible for accepting email for a domain. Each record has a priority, and sending servers try the lowest priority number first.
The priority sets the order sending servers try your mail hosts, lowest first. Equal priorities are load-balanced. It is not a quality ranking; a lower number simply means try me before the others.
No. The mail standards require an MX record to point at a hostname that has its own address records, not a CNAME alias. Some sending servers reject an MX that resolves to a CNAME, which can cause delivery failures.
A null MX is a single MX record with a priority of 0 and a target of just a dot. Defined in RFC 7505, it explicitly declares that a domain does not send or receive email, so senders reject mail to it immediately.
