When you add a new user, their email is needed so they can log in.
Initially, an invitation email is automatically sent so the new user can accept the invitation, create a password, and add their profile details. Admins can see accepted invitations when a User is marked as Active, from the Profile column in both the User Module and the Admin Settings> All Users. If you need to resend the invite or cancel, it's easy.
Click on the name of the User to open their Invitation form.
Hit the Resend Invitation or Cancel Invitation button.