php实现查看邮件是否已被阅读的方法

当你在发送邮件时，你或许很想知道该邮件是否被对方已阅读。这里有段非常有趣的代码片段能够显示对方IP地址记录阅读的实际日期和时间。
复制代码 代码如下:
<?
error_reporting(0);
Header("Content-Type: image/jpeg"); //Get IP
if (!empty($_SERVER["HTTP_CLIENT_IP"]))
{
$ip=$_SERVER["HTTP_CLIENT_IP"];
}
elseif (!empty($_SERVER["HTTP_X_FORWARDED_FOR"]))
{
$ip=$_SERVER["HTTP_X_FORWARDED_FOR"];
}
else
{
$ip=$_SERVER["REMOTE_ADDR"];
} //Time
$actual_time = time();
$actual_day = date("Y.m.d", $actual_time);
$actual_day_chart = date("d/m/y", $actual_time);
$actual_hour = date("H:i:s", $actual_time); //GET Browser
$browser = $_SERVER["HTTP_USER_AGENT"]; //LOG
$myFile = "log.txt";
$fh = fopen($myFile, "a+");
$stringData = $actual_day . " " . $actual_hour . " " . $ip . " " . $browser . " " . "";
fwrite($fh, $stringData);
fclose($fh); //Generate Image (Es. dimesion is 1x1)
$newimage = ImageCreate(1,1);
$grigio = ImageColorAllocate($newimage,255,255,255);
ImageJPEG($newimage);
ImageDestroy($newimage); ?>