现在很多主机空间都是IIS上执行PHP程序，大多不能直接用mail()发送邮件，有了这个类只要你有注册过邮箱， 就可以随意的发送邮件，速度也不慢哦。
先给一个具体的使用示例：
<?
require (FILE_DIR."smtp.php");
$smtpserver = "smtp.xxx.com";//SMTP服务器
$smtpserverport =25;//SMTP服务器端口
$smtpusermail = "xxxxx@xxx.com";//SMTP服务器的用户邮箱
$smtpemailto = "aaaaa@xxx.com";//发送给谁
$smtpuser = "xxxxx";//SMTP服务器的用户帐号
$smtppass = "xxxxx";//SMTP服务器的用户密码
$mailsubject = "Test Subject";//邮件主题
$mailbody = "<h1>This is a test mail</h1>";//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);
?>
下面是一个基于SMTP协议的邮件发送类：
<?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 $this->smtp_error("sending HELO command");
}
if($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;
}
}
}
?>