Anti-Spam with 8 layers of protection   Before even arriving into your corporate system, email is checked by the 8-layer pre-protection, a very efficient and low-CPU series of operations that detect the basic forms of spam and spammer attacks: The Protocol filter recognizes known header patterns and bounces them out automatically, without requiring any system resources.   The SMTP Security automatically scans the sender's information in search of accepted or rejected address patterns.   The Mail Relay is a configurable IP-based authorization system that lets you control who can and cannot relay email on your corporate server.   The Block Scan Attack layer counts the volume of transactions coming from a single source and either blocks or progressively slows the e-mail exchange process, thus making the server counter-productive to any spammer.   The Reverse DNS Lookup sends a request to the sender's domain IP address before it accepts any e-mail. If the IP returns a negative check, the e-mail is bounced.   The Real-Time Blacklists (or blackholes) layer compares the sender's name to different spammer blacklists and blocks any e-mail processed by a blacklisted sender. This is an optional feature that can be set according to your corporate policies.   The Connection Limit prevents a user (an IP address) to perform simultaneous operations in the server.   The Block Connections layer is a configurable filter that blocks specific IP addresses or domain names from sending e-mail.