php-邮件发送

<?php 
$to = "test@163.com"; //收件人
$subject = "Test"; //主题
$message = "This is a test mail!"; //正文 
mail($to,$subject,$message);

<?php
$to = "test@163.com";//收件人
$subject = "Test";//邮件主题 
$message = "This is a test mail!";//邮件正文 
ini_set('SMTP','smtp.163.com');//发件SMTP服务器 
ini_set('smtp_port',25);//发件SMTP服务器端口 
ini_set('sendmail_from',"admin@163.com");//发件人邮箱 
mail($to,$subject,$message);

<?php
// Pear Mail 扩展 
require_once('Mail.php'); 
require_once('Mail/mime.php'); 
require_once('Net/SMTP.php'); 
$smtpinfo = array(); 
$smtpinfo["host"] = "smtp.163.com";//SMTP服务器 
$smtpinfo["port"] = "25"; //SMTP服务器端口 
$smtpinfo["username"] = "username@163.com"; //发件人邮箱 
$smtpinfo["password"] = "password";//发件人邮箱密码 
$smtpinfo["timeout"] = 10;//网络超时时间，秒 
//登录验证
$smtpinfo["auth"] = true;
//调试模式
$smtpinfo["debug"] = true;
 // 收件人列表 
$mailAddr = array('receiver@163.com'); 
// 发件人显示信息 
$from = "Name <username@163.com>"; 
// 收件人显示信息 
$to = implode(',',$mailAddr); 
// 邮件标题 
$subject = "这是一封测试邮件"; 
// 邮件正文 
$content = "<h3>随便写点什么</h3>"; 
// 邮件正文类型，格式和编码 
$contentType = "text/html; charset=utf-8"; 
//换行符号 Linux: \n Windows: \r\n 
$crlf = "\n"; 
$mime = new Mail_mime($crlf); 
$mime->setHTMLBody($content); 
$param['text_charset'] = 'utf-8'; 
$param['html_charset'] = 'utf-8'; 
$param['head_charset'] = 'utf-8';
$body = $mime->get($param); 
$headers = array(); 
$headers["From"] = $from; 
$headers["To"] = $to; 
$headers["Subject"] = $subject; 
$headers["Content-Type"] = $contentType; 
$headers = $mime->headers($headers); 
$smtp =& Mail::factory("smtp", $smtpinfo); 
$mail = $smtp->send($mailAddr, $headers, $body); 
$smtp->disconnect(); 
if (PEAR::isError($mail)) {  
    //发送失败  
    echo 'Email sending failed: ' . $mail->getMessage()."\n"; 
} else{  
    //发送成功  
    echo "success!\n";
}