smtp.php
代码如下：

<?php
class smtp
{
    /* Public Variables */
    var $smtp_port;
    var $time_out;
    var $host_name;
    var $log_file;
    var $relay_host;
    var $debug;
    var $auth;
    var $user;
    var $pass;

    /* Private Variables */ 
    var $sock;

    /* Constractor */
    function smtp($relay_host = "", $smtp_port = 25,$auth = false,$user,$pass)
    {
        $this->debug = FALSE;
        $this->smtp_port = $smtp_port;
        $this->relay_host = $relay_host;
        $this->time_out = 30; //is used in fsockopen() 
        $this->auth = $auth;//auth
        $this->user = $user;
        $this->pass = $pass;
        $this->host_name = "localhost"; //is used in HELO command 
        $this->log_file = "";
        $this->sock = FALSE;
}

    /* Main Function */
    function sendmail($to, $from, $subject = "", $body = "", $mailtype, $cc = "", $bcc = "", $additional_headers = "")
    {
        $mail_from = $this->get_address($this->strip_comment($from));
        $body = ereg_replace("(^|(/r/n))(/.)", "/1./3", $body);
        $header .= "MIME-Version:1.0/r/n";
        if($mailtype=="HTML")
        {
            $header .= "Content-Type:text/html/r/n";
        }
        $header .= "To: ".$to."/r/n";
        if ($cc != "") 
        {
            $header .= "Cc: ".$cc."/r/n";
        }
        $header .= "From: $from<".$from.">/r/n";
        $header .= "Subject: ".$subject."/r/n";
        $header .= $additional_headers;
        $header .= "Date: ".date("r")."/r/n";
        $header .= "X-Mailer:By Redhat (PHP/".phpversion().")/r/n";
        list($msec, $sec) = explode(" ", microtime());
        $header .= "Message-ID: <".date("YmdHis", $sec).".".($msec*1000000).".".$mail_from.">/r/n";
        $TO = explode(",", $this->strip_comment($to));

        if ($cc != "") 
        {
            $TO = array_merge($TO, explode(",", $this->strip_comment($cc)));
            }
        if ($bcc != "") 
        {
            $TO = array_merge($TO, explode(",", $this->strip_comment($bcc)));
        }
        $sent = TRUE;
        foreach ($TO as $rcpt_to) 
        {
            $rcpt_to = $this->get_address($rcpt_to);
            if (!$this->smtp_sockopen($rcpt_to)) 
            {
                $this->log_write("Error: Cannot send email to ".$rcpt_to."/n");
                $sent = FALSE;
                continue;
            }
            if ($this->smtp_send($this->host_name, $mail_from, $rcpt_to, $header, $body)) 
            {
                $this->log_write("E-mail has been sent to <".$rcpt_to.">/n");
            } 
            else 
            {
                $this->log_write("Error: Cannot send email to <".$rcpt_to.">/n");
                $sent = FALSE;
            }
            fclose($this->sock);
            $this->log_write("Disconnected from remote host/n");
        }
        return $sent;
    }

    /* Private Functions */
    function smtp_send($helo, $from, $to, $header, $body = "")
    {
        if (!$this->smtp_putcmd("HELO", $helo)) 
        {
            return $this->smtp_error("sending HELO command");
        }

        #auth
        if($this->auth)
        {
            if (!$this->smtp_putcmd("AUTH LOGIN", base64_encode($this->user))) 
            {
                return $this->smtp_error("sending HELO command");
            }
            if (!$this->smtp_putcmd("", base64_encode($this->pass))) 
            {
                return $this->smtp_error("sending HELO command");
            }
        }
        if (!$this->smtp_putcmd("MAIL", "FROM:<".$from.">")) 
        {
            return $this->smtp_error("sending MAIL FROM command");
        }
        if (!$this->smtp_putcmd("RCPT", "TO:<".$to.">")) 
        {
            return $this->smtp_error("sending RCPT TO command");
        }
        if (!$this->smtp_putcmd("DATA"))
        {
            return $this->smtp_error("sending DATA command");
        }
        if (!$this->smtp_message($header, $body)) 
        {
            return $this->smtp_error("sending message");
        }
        if (!$this->smtp_eom())
        {
            return $this->smtp_error("sending <CR><LF>.<CR><LF> [EOM]");
        }
        if (!$this->smtp_putcmd("QUIT")) 
        {
            return $this->smtp_error("sending QUIT command");
        }
        return TRUE;
    }

    function smtp_sockopen($address)
    {
        if ($this->relay_host == "") 
        {
            return $this->smtp_sockopen_mx($address);
        } 
        else
        {
            return $this->smtp_sockopen_relay();
        }
    }

    function smtp_sockopen_relay()
    {
        $this->log_write("Trying to ".$this->relay_host.":".$this->smtp_port."/n");
        $this->sock = @fsockopen($this->relay_host, $this->smtp_port, $errno, $errstr, $this->time_out);
        if (!($this->sock && $this->smtp_ok())) 
        {
            $this->log_write("Error: Cannot connenct to relay host ".$this->relay_host."/n");
            $this->log_write("Error: ".$errstr." (".$errno.")/n");
            return FALSE;
        }
        $this->log_write("Connected to relay host ".$this->relay_host."/n");
        return TRUE;;
    }

    function smtp_sockopen_mx($address)
    {
        $domain = ereg_replace("^.+@([^@]+)$", "/1", $address);
        if (!@getmxrr($domain, $MXHOSTS)) 
        {
            $this->log_write("Error: Cannot resolve MX /"".$domain."/"/n");
            return FALSE;
        }
        foreach ($MXHOSTS as $host) 
        {
            $this->log_write("Trying to ".$host.":".$this->smtp_port."/n");
            $this->sock = @fsockopen($host, $this->smtp_port, $errno, $errstr, $this->time_out);
            if (!($this->sock && $this->smtp_ok())) 
            {
                $this->log_write("Warning: Cannot connect to mx host ".$host."/n");
                $this->log_write("Error: ".$errstr." (".$errno.")/n");
                continue;
            }
            $this->log_write("Connected to mx host ".$host."/n");
            return TRUE;
        }
        $this->log_write("Error: Cannot connect to any mx hosts (".implode(", ", $MXHOSTS).")/n");
        return FALSE;
    }

    function smtp_message($header, $body)
    {
        fputs($this->sock, $header."/r/n".$body);
        $this->smtp_debug("> ".str_replace("/r/n", "/n"."> ", $header."/n> ".$body."/n> "));
        return TRUE;
    }

    function smtp_eom()
    {
        fputs($this->sock, "/r/n./r/n");
        $this->smtp_debug(". [EOM]/n");
        return $this->smtp_ok();
    }

    function smtp_ok()
    {
        $response = str_replace("/r/n", "", fgets($this->sock, 512));
        $this->smtp_debug($response."/n");
        if (!ereg("^[23]", $response)) 
        {
            fputs($this->sock, "QUIT/r/n");
            fgets($this->sock, 512);
            $this->log_write("Error: Remote host returned /"".$response."/"/n");
            return FALSE;
        }
        return TRUE;
    }

    function smtp_putcmd($cmd, $arg = "")
    {
        if ($arg != "") 
        {
            if($cmd=="") 
            {
                $cmd = $arg;
            }
            else
            {
                $cmd = $cmd." ".$arg;
            }
        }
        fputs($this->sock, $cmd."/r/n");
        $this->smtp_debug("> ".$cmd."/n");
        return $this->smtp_ok();
    }

    function smtp_error($string)
    {
        $this->log_write("Error: Error occurred while ".$string."./n");
        return FALSE;
    }

    function log_write($message)
    {
        $this->smtp_debug($message);
        if ($this->log_file == "")
        {
            return TRUE;
        }
        $message = date("M d H:i:s ").get_current_user()."[".getmypid()."]: ".$message;
        if (!@file_exists($this->log_file) || !($fp = @fopen($this->log_file, "a"))) 
        {
            $this->smtp_debug("Warning: Cannot open log file /"".$this->log_file."/"/n");
            return FALSE;;
        }
        flock($fp, LOCK_EX);
        fputs($fp, $message);
        fclose($fp);
        return TRUE;
    }

    function strip_comment($address)
    {
        $comment = "/([^()]*/)";
        while (ereg($comment, $address)) 
        {
            $address = ereg_replace($comment, "", $address);
        }
        return $address;
    }

    function get_address($address)
    {
        $address = ereg_replace("([ /t/r/n])+", "", $address);
        $address = ereg_replace("^.*<(.+)>.*$", "/1", $address);
        return $address;
    }

    function smtp_debug($message)
    {
        if ($this->debug) 
        {
            echo $message;
        }
    }

}
?>

测试程序
代码如下：

<?php
/*
这是一个测试程序!!!
*/
require("smtp.php");
##########################################
$smtpserver = "smtp.163.com";//SMTP服务器
$smtpserverport = 25;//SMTP服务器端口
$smtpusermail = "reterry123@163.com";//SMTP服务器的用户邮箱
$smtpemailto = "dxytools@gmail.com";//发送给谁
$smtpuser = "reterry123";//SMTP服务器的用户帐号
$smtppass = "014040001";//SMTP服务器的用户密码
$mailsubject = "中文";//邮件主题
$mailbody = "<h1>中文</h1>测试下能淤泥新年感";//邮件内容
$mailtype = "HTML";//邮件格式（HTML/TXT）,TXT为文本邮件
##########################################
$smtp = new smtp($smtpserver,$smtpserverport,true,$smtpuser,$smtppass);//这里面的一个true是表示使用身份验证,否则不使用身份验证.
$smtp->debug = TRUE;//是否显示发送的调试信息
$smtp->sendmail($smtpemailto, $smtpusermail, $mailsubject, $mailbody, $mailtype);
?>