[EMAIL PROTECTED] said: > Well.. I can also grep "From:" to see wich addresses are sending more > mails than usual, don't I?
You're joking, right? From: is easily faked, and any bulk spammer fakes it. Unless you block your clients from sending on port 25, you can't tell what mail they're sending. If you do block port 25, I wouldn't expect your commercial clients to be happy. If you force (by firewall rules or otherwise) them to use mail.bigisp.com as their outgoing relay, they might feel you're invading their privacy. Would you want someone checking your phone calls (for other than billing purposes)?
