By default Cloze will track whether a message has been opened or any link with in your email has been clicked.
Please note email open tracking is premium feature. You can subscribe to Cloze Pro to utilize this feature.
If you toggle tracking to the off position (unfilled bell icon) the next time you reply or compose an email tracking will remain off until you enable it again. It is local to each device - so you'll need to do this for each device that is connected to Cloze.
Look for the toggle in the lower right of the email composer.
To turn this feature on, tap on the bell icon so that it IS filled in.
To turn this feature off, tap on the bell icon so that is NOT filled in.
If you wish to turn off link tracking you can tap and hold for a few seconds and more options will appear that you can disable or enable.