I'm afraid it isn't that simple, as this connection may not even be a Blockland user, just an IP sending random data.
Someone made mitterdoo make a connect-spam ban addon named Server_ConnectSpamBan, but it uses AutoAdminCheck for its purposes which I'm guessing requires the user to fully connect first.
The DaProgs RTB archive seems to be down so download said addon
here if you want to investigate.
Crap, I've been ninja'd, but I'll leave this here.