If you simply close the browser window, because of a number of technical reasons, we can not exactly determine if the window was closed to exit the application or there was just a connectivity hiccup. Therefore we keep application running on the server for some time (10 min for users on the Starter plan, 30 min for users with Premium subscription). If it was a connectivity glitch, you browser will reconnect to the app and you will continue working as usual.
However, if you indeed intended to close the app and do not reconnect to it, we will terminate the application running on the server after 10 or 30 minutes. When we do so, there is a risk that unsaved data may be lost because the application will not be able to show confirmation message like “Your document contains unsaved changes. Do you really want to close application without saving?” since you are disconnected.
When we have to terminate the application, we will send an email to notify you about this event. To avoid these emails and more importantly make sure all your changes are saved, we recommend to always close applications using File > Exit.