출처: http://www.linuxquestions.org/questions/showthread.php?t=359033
        http://pear.php.net/package/Mail
아래 소스는
http://www.linuxquestions.org/questions/showthread.php?t=359033
에서 가져 왔고
Mail_smtp 클래스는
http://pear.php.net/package/Mail
에서 받으시면 됩니다.

<?php

include('Mail/smtp.php');

class MailHandler{
var $params = null;
var $mail_object = null;
var $recipients = null;
var $headers = null;
var $body = "";

function MailHandler($host, $port, $auth, $username, $password, $persist) {
$this->params["host"] = $host;
$this->params["port"] = $port;
$this->params["auth"] = $auth;
$this->params["username"] = $username;
$this->params["password"] = $password;
$this->params["persist"] = $persist;

// Create the mail object using the Mail::factory method
//$this->mail_object =& Mail::factory('smtp', $this->params);
$this->mail_object = new Mail_smtp($this->params);
}

function createFrom($email){
$this->headers['From'] = $email;
}

function createTo($email){
$this->headers['To'] = $email;
$this->recipients = array($email);
}

function createCC($email){
$this->headers['Cc'] = $email;
}

function createBCC($email){
$this->headers['Bcc'] = $email;
}

function createSubject($sub){
$this->headers['Subject'] = $sub;
}

function createBody($body){
$this->body=$body;
}

function sendMail(){
if ($this->mail_object->send($this->recipients, $this->headers, $this->body)) {
return true;
}
else{
return false;
}
}
}


$smtpserver_host = "localhost"; // The server to connect. Default is localhost
$smtpserver_Port = 25; // The port to connect. Default is 25
$smtpserver_auth = FALSE; // Whether or not to use SMTP authentication. Default is FALSE
$smtpserver_username = "username"; // The username to use for SMTP authentication.
$smtpserver_password = "password"; // The password to use for SMTP authentication.
$smtpserver_persist = FALSE; // Indicates whether or not the SMTP connection should persist over multiple calls to the send() method.
$mailhandler=new MailHandler($smtpserver_host, $smtpserver_Port, $smtpserver_auth, $smtpserver_username, $smtpserver_password, $smtpserver_persist);

$mailhandler->createTo("toaddress");
$mailhandler->createFrom("fromaddress");
$mailhandler->createSubject("subject");
$mailhandler->createBody("body");

if($mailhandler->sendMail()){
echo "Mail sent.n";
}
else{
echo "Error sending mail!n";
}

?>

출처 : http://www.sir.co.kr/bbs/board.php?bo_table=pl_php&wr_id=333&page=4