I couldn't do it in the UI but I was able to using this SQL query (on PostgreSQL):
select spacename from spaces where creator in (select user_key from user_mapping where lower_username not in (select lower_user_name from cwd_user));
The creator column in the spaces table is a user_key that still exists in the user_mapping table when the user is deleted from LDAP (then becomes Unknown User in Confluence). The user is deleted from the cwd_user table so any space with a key that appears as a creator in the spaces table but the user is not in cwd_user, was created by Unknown User.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.