Registrations from users that don't post

[admin]

Can anyone tell me why this forum gets thousands of registrations from users that don't post?

If they are spam registrations then it is quite strange because they don't even put a website in their user profile. And they don't post so they aren't spamming that way so it leaves me a little baffled.

Warning to everyone!
I've enable user pruning so if you don't post withing 7 days your account will be deleted. Almost 3000 inactive accounts got deleted after doing this so that gives you an idea of what I'm talking about.

Edit: the prune limit has been decreased to 7 days... so you have to post withing 7 days. It won't stop the spammers but it helps.