DidTheyReadIt VS Trackapp.io

ReadNotify - ReadNotify enables the user to know when email is sent and the reciever reads the email.

Pointofmail.com - Know who, when and where read, clicked and forwarded your email.

Bananatag - Find out what happens to your emails after you press send! Add email tracking, attachment tracking, email scheduling and templates to your daily emails.

Intelliverse Email Tracker - Intelliverse Email Tracker provides insights to increase the ​productivity of your emails.

MailChimp - MailChimp is the best way to design, send, and share email newsletters.

GetNotify - GetNotify is a free email tracking software solution.