Proofpoint Dynamic Reputation (PDR) is designed to evaluate the reputation of the sending host at the connection level, using the sender’s IP address as the core signal. In Proofpoint’s own public description of PDR, the technology uses many features to determine the reputation of a particular IP and delays or blocks mail when that IP shows indications of spam activity. That means PDR is not primarily a user training feature, not a user-defined inbox rule engine, and not a simple keyword scanner of message body text. Its job is to assess the sending MTA before full message acceptance and use that reputation to influence how the system handles the connection. This is exactly why PDR is valuable in early-stage filtering: it helps reduce unwanted traffic before deeper content analysis takes place. Proofpoint’s spam architecture also describes a multilayered defense where connection-level analysis includes Dynamic Reputation alongside SPF, recipient verification, and other connection checks. In practical administrator terms, PDR is part of the front-line evaluation of the source system’s trustworthiness, helping the platform identify suspicious or compromised senders quickly and efficiently. That makes the correct answer the option focused on assessing the sending MTA’s reputation by IP address.