Introduction

The Cisco IronPort Email Security Appliances (ESA) have been deployed in thousands of networks to accept, filter, and deliver email messages. The ESA is easy to deploy and its security-filtering settings are effective right out of the box. However, many organizations are looking for more from their messaging environment and have barely tapped the potential of the ESA product line.

Email on the Internet is powered by the Simple Mail Transfer Protocol (SMTP). The simplicity of the protocol is its strength and weakness. Lack of authentication and the notion that one should accept all messages, gracefully, means that it is the most abused protocol on the Internet today. Spam is the most obvious form of abuse, but other dangers lurk, like bounce storms that can force servers offline in a denial of service (DoS) attack. Many organizations struggle with having email messages rejected or dropped by overzealous filtering.