Email tracking allows users to know when their recipient opens and reads their emails. In Gmail, you can use email receipts to know if your email has been opened. However, that depends on whether your recipient sends a return ticket to let you know if they have read your email.
Doubletick is a tool that gives Gmail users the power to build and maintain relationships in this crowded, competitive inbox environment. When your email is opened, you can see blue tick marks as an indicator that the recipient has read your email. Users also get real-time desktop notifications when the recipient opens and reads the email.