I imagine you've done some of these already, but just in case you haven't:
Comb through your request queue project to check:
- Project settings
- Share settings
- Routing rules
In the Setup area, confirm that the Email Notifications are configured as you need. I wonder if there is some sort of email notification associated with the Team's Home Group.
You might shadow a user who is experiencing these emails to check how they've configured their email notifications in their personal preferences.
Otherwise, I'd contact support to find what might be a needle in a haystack.