Spam filtering / Sieve on bulletinboards

[Andre Plante]

Hi All,
I have recently setup some bulletin boards, which are designed to
receive mail from our external clients alerting us of issues.
What I am now trying to do, but can't find any references on how to do
this, is setup sieve filtering of the messages so that the messages that
are likely spam (as judged by spamassassin) as automatically moved into
a seperate folder.
Can this be done?
We are using cyrus-imap version 2.2.12 on our mail server.
Thanks,
Andre