E-Mail Tracker is one of utility app for iOS, simple and convenient interface that sends you as a notification when emails are opened from which devices.
It covers my personal needs and the app itself is use-worthy for those who are willing to know if their e-mail opened or not.
I didn't understand the concept at first. It can be supported with an informative video.
An awesome life hackUmut Baran Zorlu has never used this product.