Currently, I rely on Gmail to weed out SPAM because the anti-spam software on my hoster's mail server is so crappy, and besides, it doesn't provide a good web UI so users can tag false negatives and improve its recognition rate.
But I don't like to depend on Gmail, especially for sensitive corporate e-mails, and I was wondering if there were open-source anti-spam solutions that were as good, or close to Gmail's?
Thank you.