Removing your email from the email server (including one configured with pop3 protocol) without actually downloading it (moving it from server to your machine) is not going to help you fight spam. If the server has accepted the email for delivery, then it's already in your inbox. It's being held for you.

Downloading the email using a client application (Mail.app, Outlook, Eudora, etc), and then deleting it, is the same as deleting it directly from the server. The email has been delivered. The email server has already accepted the email for delivery.

Deleting your email directly from the server does not make a spammer think that his/her email can't get through to you. When your email server/service accepts the message for delivery, the spammer marks your email address as 'valid'.

While this application may function well (as designed), and it may help you prevent trojan/virus infection, it will not help you fight/reduce spam.