You accomplish this feature from our admin website.

Once you are logged in, click on the "Rules" link.

Now click on the "Bayes Settings" link. The following screen should appear.

Bayes filters calculate the probability that a certain message is spam. This results in a percentage, between 0% and 100%. From here you can change which percentages customize which percentages map to which scores.

For example: Say anything with a spam score of 4 or more is quarantined as spam. If you want to tighten your Bayes filters, you could set 70% equal to a score of 5. This would cause messages to be filtered if the system determines there's at least a 70% probability that it is spam.