'http://soapinterop.org/', 'from' => 'shanec@ActiveState.com', 'host' => 'smtp.ActiveState.com' 'port' => 25); $return = $soapclient->call('echoStringArray', array('inputStringArray' => array('good','bad','ugly')), $options); // don't expect much of a result! print_r($return); ?>]]> The Message ID is the result of the SOAP call: cf4af6d730f1f9ef0cb0309bf9680c23.soap@smtp.ActiveState.com