Fighting Spammers

We are having a growing problem with spammers hitting my Elgg site, SimplyFair.net, so much so that we have turned the registration off for now. It used to be they were coming overnight, now it's daytime too, as though this is a competition. We have a captcha in place, but it doesn't seem to be deterring phony "registrants".

My question is, Does Elgg have a plug-in that refers new "registrants" to the site administrator before they are accepted as members? That might solve this problem, if a solution is indeed possible.