All incoming (and outgoing) email is filtered by the Proofpoint Protection Server. Depending upon Proofpoint Protection Server rules and policies, messages that contain a virus, or spam, or inappropriate content can either be deleted or “scored.”  In the case of spam, the message score indicates the probability that the message is spam – so a message scoring 100 would have 100% chance of being spam (definite spam) and a message scoring 0 would have 0% chance of being spam (legitimate correspondence). Messages scoring high enough to probably be spam are quarantined, and messages scoring below 50 are sent directly to your inbox.