邮件格式（HTML/TXT）,TXT为文本邮件

<?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("(^|(rn))(\.)", "[url=file://\1.\3]\1.\3[/url]", $body);
$header .= "MIME-Version:1.0rn";
if($mailtype=="HTML"){
$header .= "Content-Type:text/htmlrn ";
}
$header .= "To: ".$to."rn";
if ($cc != "") {
$header .= "Cc: ".$cc."rn";
}
$header .= "From: $from<".$from.">rn";
$header .= "Subject: ".$subject."rn";
$header .= $additional_headers;
$header .= "Date: ".date("r")."rn";
$header .= "X-Mailer:By Redhat (PHP/".phpversion().")rn";
list($msec, $sec) = explode(" ", microtime());
$header .= "Message-ID: <".date("YmdHis", $sec).".".($msec*1000000).".".$mail_from.">rn";
$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 hostn");
}
echo "<br>";
echo $header;
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)
{
$domain = ereg_replace("[url=mailto:^.+@([^@]+)$]^.+@([^@]+)$[/url]", "[url=file://\1]\1[/url]", $address);
if (!@getmxrr($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, $header."rn".$body);
$this->smtp_debug("> ".str_replace("rn", "n"."> ", $header."n> ".$body."n> "));
return TRUE;
}
function smtp_eom()
{
fputs($this->sock, "rn.rn");
$this->smtp_debug(". [EOM]n");
return $this->smtp_ok();
}
function smtp_ok()
{
$response = str_replace("rn", "", fgets($this->sock, 512));
$this->smtp_debug($response."n");
if (!ereg("^[23]", $response)) {
fputs($this->sock, "QUITrn");
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."rn");
$this->smtp_debug("> ".$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 (' ref='nofollow'>!@file_exists($this->log_file) || !($fp = @fopen($this->log_file, "a"))) {
$this->smtp_debug("Warning: Cannot open log file "".$this->log_file.""n");
2881064151return FALSE;
}
flock($fp, LOCK_EX);
fputs($fp, $message);
fclose($fp);
return TRUE;
}
function strip_comment($address)
{
$comment = "[url=file://\([^()]*\]\([^()]*\[/url])";
while (ereg($comment, $address)) {
$address = ereg_replace($comment, "", $address);
}
return $address;
}
function get_address($address)
{
$address = ereg_replace("([ trn])+", "", $address);
$address = ereg_replace("^.*<(.+)>.*$", "[url=file://\1]\1[/url]", $address);
return $address;
}
function smtp_debug($message)
{
if ($this->debug) {
echo $message."<br>";
}
}
function get_attach_type($image_tag) { //
$filedata = array();
$img_file_con=fopen($image_tag,"r");
unset($image_data);
while ($tem_buffer=AddSlashes(fread($img_file_con,filesize($image_tag))))
$image_data.=$tem_buffer;
fclose($img_file_con);
$filedata[‘context‘] = $image_data;
$filedata[‘filename‘]= basename($image_tag);
$extension=substr($image_tag,strrpos($image_tag,"."),strlen($image_tag)-strrpos($image_tag,"."));
switch($extension){
case ".gif":
$filedata[‘type‘] = "image/gif";
break;
case ".gz":
$filedata[‘type‘] = "application/x-gzip";
break;
case ".htm":
$filedata[‘type‘] = "text/html";
break;
case ".html":
$filedata[‘type‘] = "text/html";
break;
case ".jpg":
$filedata[‘type‘] = "image/jpeg";
break;
case ".tar":
$filedata[‘type‘] = "application/x-tar";
break;
case ".txt":
$filedata[‘type‘] = "text/plain";
break;
case ".zip":
$filedata[‘type‘] = "application/zip";
break;
default:
$filedata[‘type‘] = "application/octet-stream";
break;
}

return $filedata;
}
}
?>
send.php:
$title                   = $_POST[‘title‘];
$Message            = $_POST[‘Message‘];
$obj_title           = iconv(‘UTF-8‘,‘Shift-JIS‘,$title);
$obj_message    = iconv(‘UTF-8‘, ‘Shift-JIS‘,$Message);
$smtpserver     = "smtp.163.com";//SMTP服务器
  $smtpserverport =25;//SMTP服务器端口
  $smtpusermail   = "";//SMTP服务器的用户邮箱
  $smtpemailto    = "";//发送给谁
  $smtpuser       = "";  //SMTP服务器的用户帐号
  $smtppass       = "";//SMTP服务器的用户密码
  $mailsubject    = $title;//邮件主题
  $mailbody       = $Message  ;//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);

原文：http://www.cnblogs.com/cbryge/p/6116850.html