How do email analytics work?

Question

While I haven't actually used it, an email analytics web app called Litmus claims to be able to track:

1. How long someone takes to read an email.
2. Whether it is forwarded.
3. Whether it is deleted.
4. Whether it is printed.
5. What email client was used to read it.

I'm curious about where it gets this information from. Most email clients i've seen don't even load external images without explicitly loading them, let alone javascript.

Even if a lot just support images, that wouldn't give away items 1-3.

Answer 1

Any email analytics application I've seen use an image tracker. Basically if you attach a code generated 1x1 px image somewhere in the email, then during the loading of that image on the server side, you capture all of the ServerVariables

http://msdn.microsoft.com/en-us/library/ms524602%28VS.90%29.aspx

EDIT:

I just read some of the information on the Litmus website an it looks as though it confirms what I wrote above regarding image tracking

Answer 2

Here's my best guess. As this link rockinthesixstring posted says, it relies on images but not javascript.

How long someone takes to read an email.

Place several images in the email that take a while to load, if the email is read for a long time, more are loaded.

Whether it is forwarded.

Is the image loaded from more than one IP/user agent?

Whether it is deleted.

The screenshots show this combined with glanced.

Whether it is printed.

Add a background image bug to a print stylesheet.

What email client was used to read it.

Check the user agent.