Yes. There is an option to toggle on or off email open tracking along the bottom of the Cloze email composer.
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 off, tap on the bell icon so that is NOT filled in.
To turn this feature off, tap on the bell icon so that it IS filled in.