PHP Functions Essential Reference

getmxrr

bool getmxrr(string host, array reference mx_hosts, 
 [array reference mx_host_weights]) 

host	Hostname or IP address
mx_hosts	Reference to a variable that will store the array of MX hostnames
mx_host_weights	Reference to a variable that will store the array of MX host weights

Gets the MX records for a host.

Returns:

TRUE on success; FALSE on error

Description:

getmxrr() performs an MX lookup on the specified hostname and returns TRUE on success.Arrays of the MX hostnames and weights are placed in the mx_hosts and mx_host_weights arguments. Both the mx_hosts and mx_host_weights arguments must be passed as references, as in &$mx_hosts and &$mx_host_weights. The weights indicate which MX host to try first, starting with the lowest value. ...