int getmxrr (string hostname, array mxhosts [, array
weight])
Searches DNS for MX records corresponding to hostname. Returns true if any records are found; returns false if no records were found or if an error occurred.
A list of the MX records found is placed into the array mxhosts. If the weight array is given, it will be filled with the weight information gathered.
See also checkdnsrr(), gethostbyname(), gethostbynamel(), gethostbyaddr(), and the named(8) manual page.