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Introduction > Goals and Methods - Pg. xxiii

xxiii 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 organiza- tions 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 dan- gers 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. The requirements laid on SMTP have changed over the years: Most businesses consider email to be their most important communication medium, ranking above telephone. Spam volumes have increased and changed form, and legitimate message traffic is grow- ing in size and complexity as HTML has come to be the dominant format and the use of attachments has become widespread. New standards, such as SPF and DKIM, promise to bring proper authentication to email messages.