The Work Summary emails let users know how much work they did during a day, offering a list of all tasks that were being edited or created by them on all boards. It also provides information on what other team members were up to - that goes for only those team members, that you have a shared board with.
The time of the email’s arrival can be set in My Profile - Edit my details, under Send me daily work summary at. To disable these emails, just choose never in the Send me daily work summary at option. You may also use the Unsubscribe link below one of these emails to stop receiving them altogether.
Mass user Work Summary email preference management
It is also possible for an Account Admin to edit other users’ Work Summary email preferences. Just go to the People tab and hit the edit button for a specific team member. In the options available, you’ll find a Send daily work summary at: option.
The team member can still change this for themselves in their Profile settings - the last change made will be kept as active. This is a great way of managing information flow for your team when setting up a new project, while still leaving individual employees a choice in their email updates.