Is there any way to determine unused blogs in a WordPress MU install? I know that is not clear enough and let me explain a bit.
I am running WPMU install with LDAP integration. We add users to LDAP and if users want, they log in to WPMU, then the LDAP plugin automatically creates the user and the blog.
I have large amount of blogs and I want to clean them in a yearly basis. I determined that some users just logged in once and never logged in again. Some users are sometimes log in but never change the blog (only "Hello world" post is present). I think it is safe to remove these, because there won't be any data loss. They can use their "Hello world" blog whenever they want, if they log in again (probably they won't).
I don't want to delete if they are using the blog (having more than 1 post, there are no "Hello world" post active and the user logs in once in a year).
The deletion process may not need to be automatic. Manual deletion will be enough.
So, I am searching for such a feature. Are there any WP internal method to determine such blogs? I can also develop a module including this feature, any tips and tricks are also welcomed.