php smtp发送邮件的函数

php实现的smtp发送邮件的函数，带smtp验证功能，有详细的注释，适合研究smtp发信的朋友参考。

完整代码如下。

<?php
/**
 * smtp发送邮件
 * site bbs.it-home.org
*/
function send_mail($to, $subject = 'No subject', $body) {
    $loc_host = "mail.server";      //发信计算机名，可随意
    $smtp_acc = "test123@163.com"; //Smtp认证的用户名
    $smtp_pass="pwdpwd";          //Smtp认证的密码，一般等同pop3密码
    $smtp_host="smtp.163.com";    //SMTP服务器地址，类似 smtp.tom.com
    $from="test123@163.com";       //发信人Email地址，你的发信信箱地址
    $deliver=$smtp_acc; //回复到指定邮箱
    $headers = "Content-Type: text/plain; charset=\"gb2312\"\r\nContent-Transfer-Encoding: base64";
    $lb="\r\n";                    //linebreak
    $hdr = explode($lb,$headers);     //解析后的hdr
    if($body) {$bdy = preg_replace("/^\./","..",explode($lb,$body));}//解析后的Body

        $smtp = array(
      //1、EHLO，期待返回220或者250
      array("EHLO ".$loc_host.$lb,"220,250","HELO error: "),
      //2、发送Auth Login，期待返回334
      array("AUTH LOGIN".$lb,"334","AUTH error:"),
      //3、发送经过Base64编码的用户名，期待返回334
      array(base64_encode($smtp_acc).$lb,"334","AUTHENTIFICATION error : "),
      //4、发送经过Base64编码的密码，期待返回235
      array(base64_encode($smtp_pass).$lb,"235","AUTHENTIFICATION error : "));
      //5、发送Mail From，期待返回250
      $smtp[] = array("MAIL FROM: <".$from.">".$lb,"250","MAIL FROM error: ");
      //6、发送Rcpt To。期待返回250
      $smtp[] = array("RCPT TO: <".$to.">".$lb,"250","RCPT TO error: ");
      //7、发送DATA，期待返回354
      $smtp[] = array("DATA".$lb,"354","DATA error: ");
      //8.0、发送From
      $smtp[] = array("From: ".$deliver.$lb,"","");
      //8.2、发送To
      $smtp[] = array("To: ".$to.$lb,"","");
      //8.1、发送标题
      $smtp[] = array("Subject: ".$subject.$lb,"","");
      //8.3、发送其他Header内容
      foreach($hdr as $h) {$smtp[] = array($h.$lb,"","");}
      //8.4、发送一个空行，结束Header发送
      $smtp[] = array($lb,"","");
      //8.5、发送信件主体
      if($bdy) {foreach($bdy as $b) {$smtp[] = array(base64_encode($b.$lb).$lb,"","");}}
      //9、发送“.”表示信件结束，期待返回250
      $smtp[] = array(".".$lb,"250","DATA(end)error: ");
      //10、发送Quit，退出，期待返回221
      $smtp[] = array("QUIT".$lb,"221","QUIT error: ");

        //打开smtp服务器端口
        $fp = @fsockopen($smtp_host, 25);
        if (!$fp) echo "<b>Error:</b> Cannot conect to ".$smtp_host."<br>";
        while($result = @fgets($fp, 1024)){if(substr($result,3,1) == " ") { break; }}

        $result_str="";
        //发送smtp数组中的命令/数据
        foreach($smtp as $req){
                //发送信息
                @fputs($fp, $req[0]);
                //如果需要接收服务器返回信息，则
                if($req[1]){
                        //接收信息
                        while($result = @fgets($fp, 1024)){
                                if(substr($result,3,1) == " ") { break; }
                        };
                        if (!strstr($req[1],substr($result,0,3))){
                                $result_str.=$req[2].$result."<br>";
                        }
                }
        }
        //关闭连接
        @fclose($fp);
        return $result_str;
}

//调用示例
#echo send_mail($_POST["email"],$tosubject,$_POST["errortext"]);
echo send_mail('mail_001@126.com','脚本学堂，欢迎大家的光临','程序员之家_bbs.it-home.org');
echo time();
?>