Respuestas del servidor SMTP

$sock = fsockopen($host, 25, $errno, $errstr, $timeout);
if(!sock)
{
echo "Connection To Mail Server Failed";
exit;
}
else
{
echo "You connected to server";
echo"<br />";
fputs($sock, "HELO ".$host."\r\n");
$reply = fgets($sock, 1024);


fclose($sock);
}

<?php
$smtp_server = fsockopen("smtp.mydomain.com", 25, $errno, $errstr, 30);
if(!$server_smtp)
{
    // We have an error, do something
    exit;
}
fwrite($smtp_server, "HELO its_me\r\n");
fwrite($smtp_server, "MAIL FROM:<me@mydomain.com>\r\n");
fwrite($smtp_server, "RCPT TO:<myfreind@hisdomain.com>\r\n");
fwrite($smtp_server, "DATA\r\n");
fwrite($smtp_server, "Received: from mydomain.com by hisdomain.com ; Thu, 03 Jan 2006 12:33:29 -0700\r\n");
fwrite($smtp_server, "Date: Thu, 03 Jan 2006 12:33:22 -0700\r\n");
fwrite($smtp_server, "From: Me <me@mydomain.com>\r\n");
fwrite($smtp_server, "Subject: The Next Meeting of the Board\r\n");
fwrite($smtp_server, "To: myfreind@hisdomain.com\r\n");
fwrite($smtp_server, "\r\nMyFreind:\r\nHow are you ?\r\n\r\n       Me.\r\n");
fwrite($smtp_server, ".\r\nQUIT\r\n");
?>