MX record lookup
Type a domain to see the mail servers that receive its email, in priority order, and which provider runs them. Free, no account.
Every record is checked in the same pass. Also: SPF record checker, DKIM checker, DMARC checker. Full domain check.
What MX records do
MX records name the servers that accept mail for a domain. Each has a priority: senders try the lowest number first and fall back to the next one when it does not answer. Two records with the same priority share the load.
yourdomain.com. MX 10 mx1.smailor.com. yourdomain.com. MX 20 mx2.smailor.com.
Common problems
No MX record: mail to the domain is tried at its A record, which is usually a web server that refuses it. An MX that points to an IP address instead of a host name is invalid. MX records left over from a previous provider split your incoming mail between two places.
A domain that sends no mail and receives none can publish a null MX (priority 0, target a single dot) so senders give up at once instead of retrying.
Questions
What does the MX priority number mean?
Lower is tried first. A server at 10 receives mail before one at 20, which only gets it when the first does not answer. The numbers themselves do not matter, only their order.
How long does an MX change take to work?
As long as the TTL of the old record, often one hour and rarely more than a day. During that time some senders still deliver to the old servers, so keep the old mailbox open until the change has spread.
Can I receive email without MX records?
Technically senders fall back to the A record of the domain, but almost no web server accepts mail, so in practice no. Publish MX records for every domain that should receive email.
Reads public DNS only. A DKIM key we cannot find is reported as not determined, never as an error. Results are kept for ten minutes.