Understanding master.cf pickup daemon parameters

[Robert Moskowitz]

I have read the man page and 
http://www.postfix.org/BUILTIN_FILTER_README.html, but don't think I got 
the why of all of it yet.

A couple howtos I have been using as guidance have the following content 
for master.cf

pickup    fifo  n       -       n       60      1       pickup
  -o content_filter=
  -o receive_override_options=no_header_body_checks


I will be using Amavisd-new, ClamAV, and SpamAssassin for content 
filtering.  There are lots of other lines scattered around that are 
specific to these filtering tools.  I think I am adding these lines to 
limit what pickup is doing as there will be other tools that will do 
more?  Is that correct?

Thank you.