200? That is bit high in my opinion, however there are other mitigating things that can effect this. One being seasonal, that junk mail is high at this time of year with the holidays. Two, spammers are getting better with their content, that Postini is passing BSB, but blocking by quarantine.
When you set up SPF, what settings did you use?
How many messages a day on average, does this user account get? Look at their reporting and see the percentages good mail, blocked and quarantine.