Use Perl, specifically Spam::Assassin. Do not reply to spam, do not bounce spam, do not do nothing but tag and delete the spam. I get hundreds of bounce/refuse messages a day from mail servers that don't bother to distinguish between the machine sending spam and the address listed in the forged From: header. I don't send spam. So sending me something is just clogging my mailbox. I'm guessing that pinging a server would have the same problem--you're likely to impact innocent third parties more than you'll eliminate spam. The two most effective ways of dealing with spam so far are testing individual mails for keys like certain phrases, addresses, URLs, etc, and testing individual mails for the probability that they are spam using Bayesian-like statistical methods. Spam::Assassin puts them both together in one package. SA will probably catch a huge percentage of the spam before you have to read it.