[exim] Spamassassin and pipe

All,

I have searched high and low for some documentation or examples on the
subject of using spamassassin in a filter file via the pipe command
but have turned up nothing (all the documents I have seen refer to the
site-wide install). I am hoping someone can help with my request.

I need to be able to have spamassassin check an email via a local
spamassassin install on my shell account (specifically I want to be
able to utilise the whitelist checking) from within a .forward filter
specification. Having read the documentation I can see that one would
probably pipe the mail to the spamassassin command; however the
default behaviour of spamassassin when run in this way is to output
the results onto STDOUT (which is treated as an error by exim's filter
processor).

So I imagine I need to pipe the results of spamassassin back into exim
for redelivery. How do I achieve this?

Many thanks,


Paul