ini_set("SMTP","diana.talente.ro");
ini_set("smtp_port","25");
ini_set("sendmail_from","admin"); //there is a user defined in MERCURY MAIL

mail($to, $subject, $message, $headers); // this line output : Warning: mail() [function.mail]: Failed to connect to mailserver at "diana.talente.ro" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set()