def valid_mx_records?
      mx_servers.each do |server|
        exchange_a_records = dns.getresources(server[:address], Resolv::DNS::Resource::IN::A)
        return true if exchange_a_records.any?
      end
      false
    end
def valid_mx_records?
      mx_servers.each do |server|
        exchange_a_records = dns.getresources(server[:address], Resolv::DNS::Resource::IN::A)
        return true if exchange_a_records.any?
      end
      false
    end
Check if the domian has valid MX records and it can receive emails.
 The MX server exists and it has valid A records.

 @return [Boolean]