Around 1997, a company named Cyber Promotions (a/k/a Cyberpromo) was the first to start spamming Internet users on a massive scale. Cyberpromo first did this from their own mail servers, relying on their ISP’s unwillingness to disconnect them. Within a short time, however, system administrators…

*** This is a Security Bloggers Network syndicated blog from The Spamhaus Project authored by The Spamhaus Team. Read the original post at: https://www.spamhaus.org/resource-hub/email-security/the-return-of-the-open-relays