Header check and script

[Richard Smits]

Hello,

I have a puzzle which I hope someone can help me with. I want to do a 
header check with postfix, and if the subject, contains a word, call a 
script or program to put the mail message in a quarantaine.

I also want to make an exception for some email recipients.

I know we can do this with amavis and spamassassin, but I don't want to 
use spamassassin. The reason for this construction is that our isp will 
implement a spamfilter, and i don't want to check the emails twice.

If the message has a spamtag in the subject, i want to put it in a 
quarantainedir. But some people want to receive their spam, so those are 
the exceptions.

So, is this possible with postfix alone, and without spamassassin ?

Any hints are welcome....

Thanks...

Richard Smits