One gathers e-mail addresses, and the other is a powerful administrative interface. You can handle an unlimited number of mailling lists, and the administrative page features a list pruner and form letter editor. This script will check if an email address is already in the database before adding it in. Also, a member can unsubscribe directly from your website. When you want to send email to all the addresses in your list, you goto the mail.cgi file where you enter your message in the from provided, enter your password and then submit and email is sent to all.
Users can also delete their address from the list when ever they feel like it.