More Information:

This plugin has a lot features. They are all explained on the 
main site (http://www.economysizegeek.com/?page_id=395).

Install:
Make sure all postie code is its own directory inside of wp-content/plugins/postie
Make two directories in your main wordpress directory wp-filez and wp-photos
Make sure these directories are writable by your web server (chmod 777 or chown to the webserver)
make sure that the postie directory  that this file is in is moved to yourwebsite/wp-content/plugins
Login to WordPress as "admin"
Goto the Plugins tab in the WordPress Admin Site
Activate "Postie"
Goto to the "Options" tab and click on the sub-tab "Configure Postie" to configure it.
(Postie ignores the settings under Options->Writing->Writing-by-Email)


Setup a cronjob to pull down the get_mail.php
Example:
*/5 * * * * /usr/bin/lynx --source http://www.economysizegeek.com/wp-content/plugins/postie/get_mail.php >/dev/null 2>&1

This fetches the mail every five mintues.

If you don't have access to cron - check out "Cronless Postie"