Newsletter link tracking

I was working on a newsletter system, it's done now and it works fine. Today I was talking with a client about an upgrade for the 开发者_StackOverflowsystem that does the following ->

"Automatic link tracking: View who opened your email and what links they clicked on."

Now, I have an idea on how to do this to add @id variable from the user query string on each link and then add a counter on each site to see who opened the link. BUT, is it possible to do this somehow else (without the counter on each link)? And how is it possible to track who opened your mail??? I saw a couple of newsletter system websites that say they can allegedly do this...

Thank you for your time!

The only way to track who opens your emails that I can think of is to use the query string trick with the images embedded in your email. This approach is obviously fragile since viewing of inline images can be turned of in most email clients.

As was mentioned; it is not possible to track everyone who opened the email. But you can track who clicked on a specific link. The method you mentioned with the @id variable will work - but instead of embedding the actual ID in the link, I would recommend encrypting that data and not sending the actual user id in the email.

To get the users who actually opened the newsletter, you can insert a 1x1 pixel image into the email as hidden content. That pixel would come from www.myserver.com/tracker.gif?foo=bar.

Then you would look at your web server log or log this request in a database so that you can track the ones who really opened the newsletter.