Find the mail servers responsible for receiving email for any domain.
MX records list mail exchangers with a priority number. Senders try the lowest number first and fall through to higher numbers if it is unreachable. No MX usually means the domain does not receive mail.
google.com MX → 10 smtp.google.com (lowest priority first)The one with the lowest priority number.
The domain likely does not accept email, or mail falls back to its A record per RFC 5321.
Redundancy — backup servers take over if the primary is down.