Cisco Email Security Appliance

Cisco AsyncOS

All Cisco Email Security appliances are powered by the unique Cisco AsyncOS operating system for high performance and security.

Designed to meet the inbound and outbound needs of the world's largest email infrastructures, these appliances offer advanced mail delivery features such as:

  • Comprehensive queue management
  • Bounce handling
  • Connection management

These features help ensure that email infrastructure is not overwhelmed, even during the largest virus outbreaks or spam attacks. They also save money on hardware, rack space, power, and IT administration time.

Developing the Cisco AsyncOS Operating System

Cisco started with a FreeBSD kernel and made three major changes to create the Cisco Email Security appliance:

  • Developing a stackless threading model that allows the appliance to support more than 10,000 simultaneous connections, rather than the 100 connections of a traditional operating system.
  • Creating a high-performance file system and an I/O-driven scheduler optimized for the asynchronous nature of messaging (hence the name AsyncOS).
  • Designing the Cisco AsyncOS operating system to have no user-accessible UNIX shell. This makes the system highly secure and much simpler to administer. Users interact with a web-based GUI or fully scriptable command-line interface.

The Cisco AsyncOS operating system lets Cisco Email Security appliances process mail more than 10 times more efficiently than traditional UNIX systems do, providing extremely high capacity and availability.