Three separate e-mail server packages are discussed: sendmail, qmail, and Postfix. Each security topic provides hands-on examples using each of the three e-mail packages. The book primarily focuses on providing instructions for Internet Service Providers (ISPs) and small corporate network administrators for configuring Open Source e-mail packages to provide secure e-mail services to customers. Additional information educates the reader on basic e-mail principles and protocols. Some key topics that are discussed include:* @Bullet 1 = Spam blocking* @Bullet 2 =Virus filtering* @Bullet3 = Firewall configurations* @Bullet4 = Relay blocking