not sure that's practical - or even possible.
The problem is that currently, until they post, it's very hard to tell a spammer from a 'normal' member.
I do check all the new members and delete a fair number before they post - but I have to give some very odd email addresses the benefit of the doubt. It's a thin line between deleting spammers and deleting genuine members.
Given the timezone distribution of the slinging.org membership (and for our younger american members that means a lot of us Do Not Live in the states
there is always going to be a point when a spammer appears and no mods are logged on.
Equally, given that aussie is 11 hours ahead of me and I'm 8 hours ahead of chris, we do have mods around at times that an all american website would not.
Why we get so many spammers I couldn't say. It might well be the international nature of the forum, or simply the fact that we're it as far as slinging goes on the web.