you can set quarantine for each spamfilter policy. When you add en email domain you set the default spamfilter policy.
First, set the spamfilter policy for the email domain. After that go to Email->Spamfilter->Policy and click on the policy name.
In quarantine tab you can set the email address where spam will be forwarded. i.e email@example.com
Next, set your tag level. What level? Well, it's your choice. I'm using tag2 4.5 and kill level 6. Also I set spam tag level to -999 to ensure that every email is analyzed.
You will get a full report for every spam/virus email that match with your tag level. Simple and powerful!