You can send mail to your affiliates by clicking on "Mail to Members" in your Admin Control Panel. You then need to enter a password as an extra security measure. This password is "guerr1lla" You can change it in the mail_password.txt file.
You can also send mail to your customers by clicking on "Mail to Customers" in your Admin Control Panel. You can limit the customers that you send to by checking the country, and subscribe date checkboxes. You will also have to enter the "guerr1lla" password to send the message.
The requirement for the mailer is that CDONTS or SendMail or JMAIL is installed on your server.