PHP使用socket发送email！

//封装发送
function _genHeader($to,$from,$subject){
    $header = "MIME-Version:1.0\r\n";//协议版本
    $header.= "Content-Type:text/html;charset='utf-8'\r\n";//编码类型
    $header.= "Subject:".$subject."\r\n";//邮件主题
    $header.= "From:Dragoners.Li<".$from.">\r\n";//发件人
    $header.= "To:".$to."\r\n";//收件人
    $header.= "Date:".time()."\r\n";//发送时间
    return $header;
}

$socket = socket_create(AF_INET,SOCK_STREAM,SOL_TCP);
 
$conn = socket_connect($socket,'smtp.163.com','25');
$msg = '';
if($conn){
    $msg .= socket_read($socket,1024)."<br>";
            socket_write($socket,"HELO 123  \r\n");
    
    $msg .= socket_read($socket,1024)."<br>";
            socket_write($socket,"AUTH LOGIN ".base64_encode('l1623283744@163.com')."\r\n");
    $msg .= socket_read($socket,1024)."<br>";
            socket_write($socket, base64_encode('Li122400')."\r\n");
    $msg .= socket_read($socket,1024)."<br>";
            socket_write($socket,"MAIL FROM:<l1623283744@163.com> \r\n");
    $msg .= socket_read($socket,1024)."<br>";
            socket_write($socket,"RCPT TO:<865196792@qq.com> \r\n");
    $msg .= socket_read($socket,1024)."<br>";
            socket_write($socket,"DATA\r\n");
    $msg .= socket_read($socket,1024)."<br>";
    $to = "865196792@qq.com";
    $from = "l1623283744@163.com";
    $subject = " hello,world";
    $body = "这是一封测试邮件！test by Dragoners.Li~";
    $data = _genHeader($to,$from,$subject)."\r\n".$body;
            socket_write($socket,$data);
            socket_write($socket,"\r\n.\r\n");//.表示内容结束 
    $msg .= socket_read($socket,1024)."<br>";
            socket_write($socket,"QUIT\r\n");//.表示内容结束 
    $msg .= socket_read($socket,1024)."<br>";
            
}else{
    $msg = 'socket connect failed！';
}
echo $msg;