If your course uses groups and students are using their groups's homepage to communicate with each other you may receive their inter-group messages as emailed notifications of annoucements in that group's space..

If you would like to stop receiving these group announcements, then you will need to turn off announcements for the course. There are two ways to do this:

Go to the course's Homepage and click the 'View Course Notifications' button from the right-hand side. This will bring up your notification settings for the specific course, where you should turn off the Announcements option
Click on the Account button from the blue navigation bar on the left-hand side of the screen and choose Notifications. Here you should click on the 'Settings for' drop-down menu and choose the name of your course, then turn off the Announcements option. More information on this process here.

If you are an Instructor on multiple courses, and depending on what you called your groups (e.g. 'Team 50' instead of 'ELEC352 2425 Team 50') , it can be hard to work out from which course the student groups relate to in order to disable the notifications. To discover the course: in an emailed notification there will be a link which says View announcement, click on this link. This should open Canvas and show you the announcement within the Group Homepage (but still not reveal the actual course's name or course code): now click on the team's name in breadcrumb trail at the top (e.g. 'Team 50'):

This will then reveal the course code: