I have random users that show up in a drop-down list when assigning cases. These are not users that we have created and they aren't showing up in the user profiles. Most of them start with an asterisk in front of the Username and almost all of them have email addresses that end in @onmicrosoft.com. The list keeps getting longer and longer and it is troublesome having to scroll through just to find our own users. Can anyone tell me why these are getting created, how do I stop it and how do I remove them?
The same thing is happening when assigning an email response to a specific queue, but I was able to remove those.
Here is an image:
