WordPress MU

I have been being bombarded with spam registrations and blog creations. So much so that I have over 6000 blogs marked as spam currently. (It has been going on for quite some time.)
I have searched the forums and did everything that has been suggested.

I have done all three things listed in the readme.txt file, also have a couple of other spam plugins running like WP-SpamFree. They just keep coming and coming. I am currently getting more than 150 registrations and as many blog creations every day.

I have also tried adding in a plug in that adds a TOS that needs to be agreed to. It slowed them for a couple hours, but then they adjusted and started coming in heavily again.

They are all being created from the main blog. All other sites have signups closed. They are all coming from different emails, some of them come in groups from certain domains, but not in huge chunks.

Does anyone have any suggestions as to what I can do to stop the spam? Other than blocking new registrations. For my blog network to work it needs to have registrations open. lol

Thanks for any help you can give me.

Are you also running buddypress? Because then you have to do slightly different things.

Do you have email domains blocked under site admin -> Options?
Have you blocked IP addresses?
Did you disable the ability for blog owners to add other users?
Got Akismet?

Hi Andrea,

I have BuddyPRess installed, but it isnt activated anywhere.

I was adding email domains in the box provided in Site Admin>Options but it wasn't doing any good. The same domains were still getting through. So I stopped adding them to the list.

I havent blocked IPs yet. Is there a way to do it within WPMU, or do I need to do that on the server?

Yes, blog owners cannot create users.

Akismet is loaded and running. So are the following:
Cookies for Comments
SABRE
WP Hashcash

And I also did that third option in the readme.txt that adds the coding into the htaccess file along with the CFC coding I added.

You do IP blocking usually at the server level depending on what type of webserver you;re running. Since you mention htaccess, I'll assume you're using apache. If you search the forums for 'deny htaccess', you should see a fair amount of discussion on how to do this. Rather surprised you're not already doing this as it's usually suggested every time this comes up. For us, usually most of the splogs being created are coming from a small group of IP addresses.

edit: I added the splogs tag to this thread if you want to see some of the previous discussion as well.