Regarding account

Question

In the admin account, we can see that some accounts are appearing automatically, 

e.g.,

 a*_.com#EXT#@*.onmicrosoft.com**

n*_.com#EXT#@*.onmicrosoft.com**,etc. 

The client is not aware of how these users are being added. Also, the names indicate external tenants. Could you help me resolve this issue?

Answer 1

Those should be Guest users, sort of the representation of an account from a different organization. They likely appeared because someone within the organization shared a file with them, or invited them in Teams. You can read here for more details: https://learn.microsoft.com/en-us/microsoft-365/admin/add-users/about-guest-users?view=o365-worldwide