You Know How I Know You Read My Email?

By  on  

I've probably mentioned this before, but I've designed and coded numerous HTML email templates for my customers. Though I currently use an email service that tracks click-throughs, bounces, and opens, it wasn't always that way. I had to rely on my own methods of tracking click-throughs and opens. Here's how you do it.

Tracking Click-Throughs: The Email HTML

<a href="http://mydomain.com/landing.php?e=email@address.com">Click here</a> for more information!

Tracking Click-Throughs: The PHP

// (inside "landing.php")

if(isset($_GET['e']))
{
	//validate and record click-through here
}

Tracking click-throughs was the easy part. All you do is attach a $_GET variable to the link and listen for that variable on the website. Simple!

Tracking Opens: The HTML

<img src="http://mydomain.com/emails/record.php?e=email@address.com" alt="Tracker" />

Tracking Opens: The PHP

// (inside "record.php")
header('Content-Type: image/gif');

if(isset($_GET['e']))
{
	//validate and record click-through here
}
	
//push out image
if(ini_get('zlib.output_compression')) { ini_set('zlib.output_compression', 'Off');	}
header('Pragma: public'); 	// required
header('Expires: 0');		// no cache
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Cache-Control: private',false);
header('Content-Disposition: attachment; filename="blank.gif"');
header('Content-Transfer-Encoding: binary');
header('Content-Length: '.filesize('blank.gif'));	// provide file size
readfile('blank.gif');		// push it out
exit();

This involves a bit more. You need to first tell the PHP file that it should be served as an image. Then, you read the $_GET variable value and record that the user had requested the file. Lastly, you push out the actual image.

Of course, this isn't the best method of email tracking. You miss bounce reports, forwards, and a host of other important stats. You do, however, get the most important information: who viewed your email?

Recent Features

  • By
    Convert XML to JSON with JavaScript

    If you follow me on Twitter, you know that I've been working on a super top secret mobile application using Appcelerator Titanium.  The experience has been great:  using JavaScript to create easy to write, easy to test, native mobile apps has been fun.  My...

  • By
    Facebook Open Graph META Tags

    It's no secret that Facebook has become a major traffic driver for all types of websites.  Nowadays even large corporations steer consumers toward their Facebook pages instead of the corporate websites directly.  And of course there are Facebook "Like" and "Recommend" widgets on every website.  One...

Incredible Demos

  • By
    jQuery Chosen Plugin

    Without a doubt, my least favorite form element is the SELECT element.  The element is almost unstylable, looks different across platforms, has had inconsistent value access, and disaster that is the result of multiple=true is, well, a disaster.  Needless to say, whenever a developer goes...

  • By
    Elegant Overflow with CSS Ellipsis

    Overflow with text is always a big issue, especially in a programmatic environment. There's always only so much space but variable content to add into that space. I was recently working on a table for displaying user information and noticed that longer strings were...

Discussion

  1. Jon

    Doesn’t this only work if I allow HTML content in my email program?

  2. @Jon: Correct. Text-only email doesn’t allow for this. Most clients are set up to allow HTML by default.

  3. Gmail also blocks all images by default.

  4. You set the Content-Type header twice, once for jpeg at the top and then again for gif.

  5. @Dan: Thank you for pointing that out. Fixed!

  6. Sebastian Otaegui

    So that is why you need to disable html in your email reader. To avoid email harvesting.

    ’nuff said.

  7. dan

    I am having problems with this script. Instead of blank image, the browser will display the broken image icon. When I look at the source I can see that IMG SRC still shows link to php tracker file.

    What am I missing? Thanks for yor help

  8. @Dan: You do have a “blank.gif” file, correct?

  9. Einer Iriarte

    Greetings and as is the “record.php” not much php, but if I want I could explain how it is please?

  10. antonio

    Hello,

    I´ve included the html code in my newsletter, and create the record.php. I can see the blank.gif but i dont know where the emails are stored and how should i do to get them.

    Regards,
    Antonio.

  11. Nice trick !
    I think on line 2 image type should be image/gif if the image is blank.gif (instead of image/jpeg) ?

    Thanks
    Sylvin

  12. Good catch Sylvin — updated.

  13. have tried eveyrthing but cannot get my to work–use a cable provide– with my old computor worked just fine–new comp s dell

  14. isa

    how comes it can be that you cant view your images on ypur email addres after more than 3 mopnths let me say that its becauyse of the HTML .So how should I go aboutthis let me call it aproblem?

  15. Didier

    Hi, the script is ok and works fine indead, but only if the client doesn’t block is images in his mail program.
    Is this correct??

  16. nabil

    hi, this post is just awesome. a Big thank you David.
    any idea about how to detect forwarded emails ? :p

  17. Raham

    Hi David Walsh!
    First of all if the user does not click on the link then…???
    Now secondly,what if the user has already disable the images in his/her mail then…???

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!