[php]smtp.class.php

<?
set_time_limit(120);
class smtp_mail
{
var $host;          //主机
var $port;          //端口 一般为25
var $user;          //SMTP认证的帐号
var $pass;          //认证密码
var $debug = false;   //是否显示和服务器会话信息？
var $conn;
var $result_str;      //结果
var $in;          //客户机发送的命令
var $from_r;          //真实的源信箱,一般与smtp服务器的用户名一样，否则可能由于smtp服务器的设置而发送不成功
var $mailformat=0; //邮件格式 0=普通文本 1=html邮件
function smtp_mail($host,$port,$user,$pass,$debug=false)
{
$this->host   = $host;
$this->port   = $port;
$this->user   = base64_encode($user);
$this->pass   = base64_encode($pass);
$this->debug = $debug;
$this->socket = socket_create (AF_INET, SOCK_STREAM, SOL_TCP); //具体用法请参考手册
if($this->socket)
{
$this->result_str = "创建SOCKET:".socket_strerror(socket_last_error());
$this->debug_show($this->result_str);
}
else
{
exit("初始化失败，请检查您的网络连接和参数");
}
$this->conn = socket_connect($this->socket,$this->host,$this->port);
if($this->conn)
{
$this->result_str = "创建SOCKET连接:".socket_strerror(socket_last_error());
$this->debug_show($this->result_str);
}
else
{
exit("初始化失败，请检查您的网络连接和参数");
}
$this->result_str = "服务器应答：<font color=#cc0000>".socket_read ($this->socket, 1024)."</font>";
$this->debug_show($this->result_str);


}

function debug_show($str)
{
if($this->debug)
{
echo $str."<p>\r\n";
}
}

function send($from,$to,$subject,$body)
{
if($from == "" || $to == "")
{
exit("请输入信箱地址");
}
if($subject == "") $sebject = "无标题";
if($body    == "") $body    = "无内容";

$All          = "From:".$from."\r\n";
$All          .= "To:".$to."\r\n";
$All          .= "Subject:".$subject."\r\n";
if($this->mailformat==1) $All.= "Content-Type: text/html;\r\n";
else $All .= "Content-Type: text/plain;\r\n";
$All          .= "charset=gb2312\r\n\r\n";
$All          .= $body;
/*
如果把$All的内容再加处理，就可以实现发送MIME邮件了
不过还需要加很多程序
*/


//以下是和服务器会话
$this->in       = "EHLO HELO\r\n";
$this->docommand();

$this->in       = "AUTH LOGIN\r\n";
$this->docommand();

$this->in       = $this->user."\r\n";
$this->docommand();

$this->in       = $this->pass."\r\n";
$this->docommand();

if(!eregi("235",$this->result_str)){
   $this->result_str = "smtp 认证失败";
   $this->debug_show($this->result_str);
   return 0;
}

$this->in       = "MAIL FROM:".$from."\r\n";
$this->docommand();

$this->in       = "RCPT TO:".$to."\r\n";
$this->docommand();

$this->in       = "DATA\r\n";
$this->docommand();

$this->in       = $All."\r\n.\r\n";
$this->docommand();

if(!eregi("250",$this->result_str)){
   $this->result_str = "邮件发送失败";
   $this->debug_show($this->result_str);
   return 0;
}

$this->in       = "QUIT\r\n";
$this->docommand();

//结束，关闭连接
return 1;
}

function docommand()
{
socket_write ($this->socket, $this->in, strlen ($this->in));
$this->debug_show("客户机命令：".$this->in);
$this->result_str = "服务器应答：<font color=#cc0000>".socket_read ($this->socket, 1024)."</font>";
$this->debug_show($this->result_str);
}

} //end class
?>


先把文件内上面程序里的这些内容填进去，如：
var $host="smtp.sina.com.cn"; //主机
var $port="25"; //端口 一般为25
var $user="users"; //SMTP认证的帐号
var $pass="users123; //认证密码

然后把这个文件放到你网站下，只要你网站的程序访问的到就行，.
然后要用到发邮件的程序里包含进来 如: include('smtp.class.php');
然后在这个发邮件的程序里用
$mails=new smtp_mail();
if($mail->send("发信人地址","收信人邮箱地址","主题","内容")){
echo "发送成功!";
}else{
echo "邮件服务器忙，请稍候再试试";
}