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"
Features:

Tips for Using:
    * If you put in :start - the message processing won't start until it sees that string
    * If you put in :end - the message processing will stop once it sees that string
    * Posts can be delayed by adding a line with delayXdXhXm where X is a number.
          delay:1d - 1 day
          delay:1h - 1 hour
          delay:1m - 1 minute
          delay:1d2h4m - 1 day 2 hours 4m
    * By putting comments:X in your message you can control if comments are allowed
          comments:0 - means closed
          comments:1 - means open
          comments:2 - means registered only


Category Handling:
    * If you put a category name in the subject with a : it will be used
      as the category for the post
    * If you put a category id number in the subject with a : it will
      be used as the category for the post
    * If you put the first part of a category name it will be posted in
      the first category that the system finds that matches - so if you put

      Subject: Gen: New News

      The system will post that in General.
 
    * All of the above also applies if you put the category in brackets []
    * Using [] or you can post to multiple categories at once

      Subject: [1] [Mo] [Br] My Subject

      On my blog it would post to General (Id 1), Moblog, and Brewing all at one time

    * Using - or you can post to multiple categories at once

      Subject: -1- -Mo- -Br- My Subject

      On my blog it would post to General (Id 1), Moblog, and Brewing all at one time


Image Handling:
    * Postie has a filter to make it easy to show full images on individual pages.
    * Tells you if you have GD installed for resizing images
    * Allows you to attach images to your email and automatically post
      them to your blog
    * Large images are automatically thumbnailed and linked to the larger
      image (Requires GD)
    * You can publish images in the text of your message by using #img1#
      #img2# - each one will be replaced with the HTML for the image
      you attached
    * Rotation - if you include the text

      rotate:90

      or any other number - all images in the message will be rotated for you.

    * Images are renamed in a way that makes it impossible to accidentally
      overwrite images you have already posted


General Features:
    * You can set the starting characters for you signature so that it
      is removed from the posting message
    * You can set a list of banned file names so if you provider adds
      images to your post they don't show up in the blog
    * If you post from an email address that is not a valid author the
      email post will be forwarded to the admin
    * You can control if you want HTML allowed in the body or subject
      of your post
    * Lets you set a default subject when you don't set one
    * Defaults to posting to the default category you set in Word Press

Interoperability:
    * If your mail client doesn't support setting the subject (nokia) you
      can do so by putting #your title here# at the begining of your message
    * POP3,POP3-SSL,IMAP,IMAP-SSL now supported - last three require
      php-imap support
    * The program understands enough about mime to not duplicate post
      if you send an HTML and plain text message
    * Automatically confirms that you are installed correctly