Thanks in advance for your help!
Here is the background for my question for those who are interested:
I just switched our domain with 100~ users from Barracuda to mailcleaner this morning and so far I am pleased. I had setup NiceBayes as active but non-decisive. I got a spam message and upon investigating I found that NicyBayes had marked it 100% spam but I couldn't see a Spamc rule using that information:
Apr 19 08:11:57 localhost MailScanner: NiceBayes result is spam (100%%) for 1UTAAV-0001KL-Ou
Apr 19 08:12:00 localhost MailScanner: Spamc result is not spam (3.1/5.0) for 1UTAAV-0001KL-Ou
Apr 19 08:12:00 localhost MailScanner: Message 1UTAAV-0001KL-Ou from 188.8.131.52 (firstname.lastname@example.org) to [mydomain].com is not spam, NiceBayes (100%%), Spamc (score=3.1, required=5.0, URIBL_BLACK 1.8, HTML_EXTRA_CLOSE 0.0, RDNS_NONE 1.3, HTML_MESSAGE 0.0, T_FRT_LITTLE 0.0, SPF_HELO_PASS -0.0, HTML_IMAGE_RATIO_08 0.0, TO_NO_BRKTS_NORDNS 0.0, T_REMOTE_IMAGE 0.0)
My temporary solution was to just make NiceBayes decisive. However, I am not sure if I completely trust NiceBayes at this point so I would really like it to just count towards the total score. I am worried about false positives.
If any of the maintainers for MailCleaner are reading, thank you for a great piece of open source software! The reason we switched from Barracuda is that our company is not doing well financially and will possibly be sold so we dropped maintenance on the Barracuda and without updates it goes downhill fast. I really think that MailCleaner will be able to do a better job of filtering when I get everything tuned right. A few of our users were still getting 10+ spams per day with the Barracuda.