[Exim] Multiple pipe questions.

Well, I've gotten tired of having to duplicate my mail sorting and filtering
rules on each client I read (imap) mail from so I'm trying to do it at the
server.

I'd like to have each message get run through 1 or more (unix) filters such as
SpamAssassin, TMDA, gpg, etc. Which filter(s) get run would be
user-configurable. Then I'd like to be able to re-examine the message after
the filter(s) have been applied to it and make delivery decisions from there.

For example, I want to have SA, TMDA and gpg run on my messages, but my wife
only wants SA. We both agree that an SA rating of 15 is spam and should be
dropped.

So, the questions are:
Can I send a message through multiple directors/routers before sending it to a
transport?

Can I send a message throught (multiple) unix filters before delivery?

Can I examine any headers that these filters may have added?

TIA,

Mike Diehl.