The Litmus' tracking code has a div with id #_t, as code bellow.
<style data-ignore-inlining=3D"" type=3D"text/css">
@media print {
#_t { background-image: url('https://ekpz8q6s.emltrk.com/ekpz8q6s?p&d=3Dcarlosfatureto@gmail.com');
}}
div.OutlookMessageHeader {
backgroun=
d-image: url('https://ekpz8q6s.emltrk.com/ekpz8q6sf&d=3Dcarlosfatureto@gmail.com');
}
table.moz-email-headers-table {
background-image: url('https://ekpz8q6s.emltrk.com/ekpz8q6s?f&d=3Dcarlosfatureto@gmail.com');
}
blockquote #_t {
background-image: url('https://ekpz8q6s.emltrk.com/ekpz8q6s?f&d=3Dcarlosfatureto@gmail.com');
}
#MailContainerBody #_t {
background-image: url('https://ekpz8q6s.emltrk.com/ekpz8q6s?f&d=3Dcarlosfatureto@gmail.com');
}
</style>
<div id="_t"> </div>
<img border="0" height="1" src="https://ekpz8q6s.emltrk.com/ekpz8q6s=?d=carlosfatureto@gmail.com" width="1" style="border: 0;height: auto !important;outline: none;text-decoration: none;-ms-interpolation-mode: bicubic;">
The "print rate" and "forwards rate" uses this div to identify if the email was printed or forwarded. But, Gmail, Outlook and everyone of the "biggest companies" removes all ids and classes from email's elements. So, without the id there is no tracking.
The "engagement rate (glanced, deleted, read, skim)" probably use a slow-load image. The time to load is the time that user spent. Once again, Gmail, Outlook and everyone of the "biggest companies" use proxy and cache. In this case, the image is always loaded until the end.
I made some tests and both methods (slow-load image and div with custom id) failed in Gmail and Outlook, but it works in roundcube webmail.
So, my question is. In 2016, someone uses Litmus and it works for you? I know that back in 2010 the Litmus probably worked fine, but now, in 2016, it still works?