A Practical Guide to Red Hat® Linux® 8

E-mail Security

E-mail security overlaps file security and, as discussed later, network security. GnuPG is the most frequently used tool for e-mail security, although you can also use PGP. PEM (Privacy Enhanced Mail) is a standard rather than an algorithm and is used less frequently.

MTAs (Mail Transfer Agents)

MTA Increasingly commonplace is STARTTLS (Start Transport Layer Security—www.sendmail.org/~ca/email/starttls.html). TLS itself usually refers to SSL (Secure Socket Layer) and has become the de facto method for encrypting TCP/IP traffic on the Internet. The sendmail utility can be built to support STARTTLS, and much documentation exists on how to do so. STARTTLS enhancements also exist for qmail and postfix and other popular MTAs. It is ...