Red Hat uses the Dovecot service for incoming e-mail. It can be configured for use with both the POP3 and IMAP protocols, as well as their secure cousins (POP3S and IMAPS). If you want to handle secure incoming e-mail, you'll want to set up SSL certificates in the /etc/pki/dovecot/certs and /etc/pki/dovecot/private directories. The mkcert.sh script is designed to help create custom certificates, using settings you add to the /etc/pki/dovecot/dovecot-openssl.cnf file.
Red Hat includes two servers for outgoing e-mail: sendmail and Postfix. Both rely on SMTP to send e-mail. The sendmail service includes difficult-to-read configuration files: sendmail.cf and submit.cf, both in the /etc/mail directory. Fortunately, you can configure these files through easier-to-read macro files, sendmail.mc and submit.mc. Postfix is somewhat easier to configure directly through its own configuration file, /etc/postfix/main.cf. Red Hat also provides a variety of e-mail clients, including mail, mutt, and the mail clients that come with the various Web browsers that are also available for Linux. These clients use either POP or IMAP protocols to receive e-mail.
Because RHCE is a performance-based exam, just like life, it is important to practice all the skills discussed in this chapter. You may need to use these skills on the exam!