What is the best way to setup Postfix so that I can guarantee only 
"approved" users gain access to the mail server?

I have been in the main.cf file and just wanted to make sure I was 
covering all the bases before I consider switching completely over to it.

Also, isn't there a way to write a Procmail recipe that would kill 
content based on the attachment type as opposed to having to write the 
recipe to look for some type of pattern?

I noticed in the replies that I saved from Procmail question I asked 
last that the script that it suggested has different entries for a 
gazillion different virii for Windoze.

Any thoughts?

Thanks!

Chris