Detailed example of how PHP determines whether the recipient has read the email

After using phpmailer to send an email, many people want to know whether the other party has read the email? Generally speaking, we cannot know this, so is there any way?

There is a simple solution to this problem. We know that the email content can be sent in the form of html, and we can insert pictures into the content, so the key lies in the picture.

Suppose the content of our email is like this:

The file content.php code is as follows:

<table width="555" height="50" border="0" align="center" cellpadding="0" cellspacing="0" background="<?=$bg?>">
<tr>
 <td>这是测试内容</td>
   </tr>
   <tr>
 <td> </td>
   </tr>
   <tr>
 <td> </td>
   </tr>
 </table>

How to write this $bg? What if the email is sent to multiple people? How to distinguish here?

Assume the link is like this: http://www.xxx.com/image.php?email=$email Look at the code of image.php again

The file image.php code is as follows:

<?php 
$email=$_GET["email"]; 
if($id) 
{ 
  include_once("/conn.php"); 
  mysql_query("update mail_list set has_read=&#39;yes&#39; where email=&#39;$email&#39;"); 
} 
header("Content/type:image/gif"); 
$im=imagecreatefromgif("bg.gif"); 
imagegif($im); 
imagedestroy($im); 
?>

You may understand after seeing this. So the content of the email I sent is like this:

<?php 
ob_start(); 
include_once("content.php"); 
$content=ob_get_contents(); 
ob_end_clean(); 
?>

Written here, we have not replaced the background image in the email content. The next problem will be gradually solved. Question, this is part of the code for sending emails using phpmail:

<?php 
/* 
$contact=array("userA"=>"aaaa@sina.com","userB""=>"bbb@163.com","userC"=>"ccc@qq.com"); 
*/ 
foreach ($contact as $unm=>$email) 
{ 
  $bg_file="http://{$_SERVER[&#39;SERVER_NAME&#39;]}/image.php?email=$email"; 
  $str=str_replace(&#39;background=""&#39;,"background=\"$bg_file\"",$content); 
  $mail->MsgHTML($str); 
  $mail->AddAddress($email,$unm); 
  $mail->Send(); 
} 
?>

Why do we need to send them one by one in a loop here? Because in order to distinguish which contact has read the email, the background image of the content of each email is displayed differently. Before sending, we process the content and replace the background, so that the src of the background image of the email content we see becomes like this: http://www.domain.com/image.php? email=aaa@sina.cometc.

Note that there is another problem here. After you execute the above code, you will find a problem. There are 3 emails sent to the first person, 2 emails to the second person, and 1 to the third person. Feng, why is this here? Let’s take a look at the AddAddress method here. The modification method is: open class.phpmailer.php, find line 310, change private $to=Array() to public $to=Array().

Then send the email Add to the code:

$mail->to=Array();
$mail->AddAddress($email,$unm);

After writing this, there is no need to explain too much.

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