We strongly recommend that you apply the default inbound annotation "Click here to report this email as spam." For new policies, this annotation is enabled by default. This gives users immediate feedback and helps us tune our spam filter for future releases. Here is the feedback that users receive when they click this link:

To aid in the process of spam tuning, when you use the "Report as spam" annotation, we recommend that you configure Forcepoint Email Security Cloud to keep a private copy of clean email messages for a short period, separate from the quarantine area (see Keep a copy of clean messages). If Forcepoint Email Security Cloud has the original message available, our operations staff and automated systems can analyze the message.