aris wrote:Spammers use humans too!
They do, but if you're getting constant and unrelenting spam signups it's more than likely bot activity. Pretty much everyone agrees that you'll never stop determined human spammers.
Toby wrote:looks like it may have worked, will give it a couple more days to clear out the rubbish and then re-instate everything
Great news.

At some point the question may be cracked again. Probably worth having another in mind for this eventuality. Also, having only one question means that you know straight away - if you had 10, for example, there might only be one that's cracked and letting the spammers through, but you wouldn't know which one.
Do you also use the newly registered users group as an extra layer of protection? I'm assuming you do as my first few posts were on admin approval.