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    dns.resolveMx(hostname, callback): void
    Attributes
    hostname:string
    callback:Function
    err:Error
    addresses:Object[]

    Uses the DNS protocol to resolve mail exchange records (MX records) for the hostname. The addresses argument passed to the callback function will contain an array of objects containing both a priority and exchange property (e.g. [{priority: 10, exchange: 'mx.example.com'}, ...]).