When you do not interact with the system for an extended period of time (30 minutes is the current default), the system identifies your connection as inactive and automatically signs you out. When you do interact with the system again, you will be redirected to the log-in page as a standard security measure.
This timeout sometimes causes inconvenience among users when creating an email campaign, usually arising when a user attempts to write an email campaign and does not save his/her work at regular intervals. Because there is no interaction (e.g. saving to the database or navigating from page to page) the system cannot identify activity and consequently ends the session.
To avoid having your session ended, simply save your work regularly and/or navigate to the next page.