It will parse the files into an object, from there you can store it into the database. If you don't have direct access, you may want to add IMAP library to get the messages: http://www.php.net/manual/en/ref.imap.php
I don't know if this will help with what I want to acomplish.
I want a system so people can retrieve information from their profile by sending an email to my website email address then the website will gather what the user wants and emails it back to them.
This should certainly be possible - as an extension of the method I outlined above. You simply tag on the 'email data out' code after the SQL query.
The only thing I'd say is that data within an email has to be formatted perfectly for it to work (i assume). SO email may not be the most effective method. An email form on your website should force certain formats. However, if you use a webform, this could be sent directly to the script without need for an email at all. The script of course could then send details of the update/request back to the user via email. No need for piping at all for that. The original request could be logged in a DB table and so could details of the 'returned email'.