Comment Internal Spam is the new problem (Score 1) 279
Here on my ISP we get the same problem from time to time. We have a very strong antispam policy regarding our own users (about 40k) and they usually understand it. Our main problem right now are hijacked user accounts. So we have systems in place the blocks users/passwords after they start sending spam, but only after a few hundred were already sent (we are improving on that shortly). While this has led to a much lower RBL block rate, we still get one from time to time. In that case we remove that mail server from our cluster for a week. You only get ASN blocked if there are too many IPs sending spams on your network. There is no other way: watch your users, specially the web hosting users (PHP's mail() should be deactivated). RBLs works on the premise that they should block any spam regardless of any other traffic you might have. Reputation systems knows better. In any case, no one will like your network as long as your users keep sending spams. Your only complaint about UCE is because they charge to unblock your IP. The others don't charge and will just not unblock it.