How to make perfect spamsnake

Hi,
I just successfully implement how-to Virtual Users And Domains With Postfix, Courier, MySQL And SquirrelMail (Ubuntu 9.04). but I got few question regarding to the administration :
1. is there a way not to mailx every new user? or mailx every new user automatically?
2. how to add mailscan, and add spamfilter (or something similiar)?
3. is there any web application to administrate this like ebox?
Thank you so much.
as a newbie, the tutorial is very easy to follow.

once again.. thanks Falko

 

Should be possible to write a script that can be run by cron, e.g. every 5 minutes.

Not that I know.