Missed Opportunities are not automatically sent to all users.
However, some users may no longer wish to receive the "missed opportunities" email notifications.
To stop receiving these emails, go to Settings>Users. Search by the name of the user and click on the edit pencil. From the left hand side of the screen, untick the option, highlighted below:
Remove the tick from the box labelled "Send email reminders for missed opportunities?" and then click on update on the top right hand corner of the screen.