User Menu > Preferences
at the bottom in the moderator/admin email notifications section:

Quote
Email me for user account related administrative actions such as:
- When a user accesses multiple accounts.
- Forum display name change requests.

current developer of UBB.threads php forum software
current release: UBB.threads 8.0.1 // wip: UBB.threads 8.1.0
isaac @ id242.com // my forum @ CelicaHobby.com