An email tracker which records when an email has been opened and how many times it has been opened, all without the inconvenience of alerting the recipient.

It is now possible for me to calculate exactly how irrelevant she considers me to be. Not opened? Oh that's bad. Opened and not replied? Oh my heart, that's worse!!

Who would design such a horror piece of software?? They have clearly never love hated their therapist. And why didn't any of you warn me?! Oh who am I kidding, you probably all have the pro paid-for versions installed.