This plugin is pretty close to what I need, but the whitelisting and user-deletion don't seem to be working properly. I'm running multisite.
My users typically don't comment, and don't log in often. I have them registering in order to enter their companies a custom adverting interface I built. So when they register and pay, I whitelist the user name.
It seems that user-spam-remover is killing off their ability to log in, though from what I can see it's not removing anyone's wp-user or wp-usermeta data, including the registration spammers. I created a test registration a couple of days ago, with a 2-day delete period set, and that test user can't log in, doesn't show up in the wp-admin/users interface, but is still there in wp-user and wp-usermeta.
It seems that they're not being attached to any particular site. I don't know if that's a function of your plugin or of WP in general. If I create the user via the Admin, they're attached to whichever site's admin page I create them with.
I'm about to launch an initiative to get more (real) users, and I'd like to get this figured out before I do that.
Thanks for any insights you might have.