Theoretically it should be possible to stop a scheduled message (SMS and email) up until 5 minutes before the scheduled send time. However, Engage will require time to stop a message and the amount of time will differ depending on the number of recipients of the given message.
The greater the number of recipients, the more time will be required for stopping. Not allowing for enough time may result in messages going out before a complete stop has been accomplished.
Stopping a message:
1. Click the Messages tab in the left-hand side menu.
2. Click Email or SMS and then Scheduled.
3. Locate the scheduled message in the list and click the stop icon.