An e-mail is spam when its calculated probability exceeds

The closer the value is to 100%, the less likely you are  to catch spam. However, the closer the value is to 0, the greater the probability that you will have false positives.

Example: Suppose this option is set to 80%. If an e-mail message is processed and the combined probability for all of the word values within it is 60% likely to be spam, then this message is identified as non-spam, because it does not meet the probability benchmark of 80%.