An MX (mail exchanger) record maps a domain name to a mail exchanger. A mail exchanger is a server that either delivers or forwards mail. You can specify one or more mail exchangers for a zone, as well as the preference for using each mail exchanger. A standard MX record applies to a particular domain or subdomain.
You can use a wildcard MX record to forward mail to one mail exchanger. For example, you can use a wildcard MX record in the corpxyz example.com domain to forward mail for eng.corpxyzexample.com and sales.corpxyzexample.com to the same mail exchange, as long as the domain names do not have any matching resource record. Wildcards only apply when the domain name being queried does not match any record.
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