The Tethernet TetherFilter offers a complete email firewall with anti-spam and anti-virus technology in an easy to deploy appliance. With accurate anti-spam technology, near-zero administration and simple deployment TetherFilter can effectively stop the deluge of spam and viruses into an email system. TetherFilter includes spam filtering, virus filtering, email firewall, RBL support, DNSRBL support, blacklists, whitelists, and filtering put together as an effective spam blocker.