MX record

An MX (mail exchanger) record is a DNS record that tells sending servers where to deliver email for a domain. Each MX record has a preference value and a hostname, for example: acme.com MX 10 mx1.acme.com and acme.com MX 20 mx2.acme.com. Senders try the lowest preference number first and fall back to higher numbers if it's unavailable.

Under RFC 5321, if a domain has no MX records, senders fall back to the domain's own A or AAAA record (the implicit MX). A domain that wants to say it accepts no email at all can publish a null MX (MX 0 .), defined in RFC 7505.

The MX hostname often reveals who hosts the domain's email, which is why it's useful for diagnosing delivery problems.

If a prospect's domain has no working mail destination, every email to it will fail, however good the address looks. Checking MX records is a fast way to drop dead domains, expired startups and typo domains (acme.con) from a list before they turn into hard bounces.

Every Skrap.ai verification checks the domain and its MX records before attempting the mailbox check over SMTP. An address whose domain can't receive mail comes back Invalid, which is free. Try it with the free email verifier, or see any domain's mail servers with the free MX lookup.