Boardeaser sends different types of mail to you as a user. Some are sent automatically by the system, and some are sent because another user has sent you a task.
Turn off reminders and notifications
To turn off automatic reminders (for example, when the date of a to-do task is approaching), click on your name at the top right and then "My profile". Uncheck the “Reminders and notifications” box to turn off all automatic reminders.
The setting only concerns automatic reminders via e-mail. You will always receive, for example, meeting invitations and messages about reviewing minutes from other people.