Yes - you change your subscription options. I am not sure you can do it from the mobile app, however.
If you log in from a normal browser, and go to user CP, click list subscriptions in the left hand column.
You can check the radio box at the top of the list of subscriptions, and scroll to the bottom and choose no email notification.
To change your default subscription mode so that future threads don't send emails, once again in user CP go to Edit Options in the left hand column, and scroll down to find default thread subscription mode. Change that box to No emails, and scroll down to the bottom and click save.
