You now have received a detailed review of what you need to know in regard to Sendmail, Procmail, Majordomo, and INN. You will find that the best thing to do now is to install these daemons and become familiar with the workings of each program. The LPI Exams are designed to test applied knowledge, and the only way you can be sure to do well is to work as closely with the applications and daemons as possible.