If a user does register an IM name when this error message is displayed then the registration is for the IM Manager service account.
1. Open the IM Manager Administration Console.
2. Click on Administration tab.
3. Click on the User Management > Modify Users page.
4. Use the search criteria to find the IM name.
5. The value in the Display Name field is the distinguished name of the IM Manager service account.
Account listed at top of Self Registration Page is the IM Manager service account account.
The following screenshot shows an account belonging to blackops-simm\benjamin_lurie:
If the account listed is the IM Manager service account then this condition applies.
Anonymous access is enabled on the IM Manager public directory in IIS.
Check if the IIS directory /immanager/public has anonymous authentication enabled.
Open the IIS Administrator MMC plugin.
Expand Web Sites|Default Web Site|immanager.
Right click on the public folder and choose Properties.
Click the Directory Security tab.
Click the Edit... button for the Authentication and access control section.
If Enable anonymous access is enabled then this condition is met.
1. Open the IIS Administrator from Start|Administrative Tools|Internet Information Services (IIS) Manager.
2. Expand the server tree on the left hand side of the snap-in.
3. Expand Sites|Default Web Site|immanager.
4. Double click on IIS|Authentication (in the main window). This brings up the list of authentication methods of the folder.
5. If Anonymous Authentication is Enabled in the Status column then this condition is met.
The IM Manager self registration page uses IIS integrated windows authentication to obtain the Active Directory logon account of the end-user. If anonymous access control is enabled then IIS defaults to using the IIS account configured for anonymous access. For the IM Manager web site the IIS anonymous account is the IM Manager service account.