Which scenario would prevent URL Defense from rewriting a URL?

URL Defense rewriting primarily targets URLs in the email body where Proofpoint can transform the link into a protected, time-of-click analyzed URL. If the URL is embedded inside a PDF attachment (A), it generally cannot be rewritten the same way because it is not a standard hyperlink in the email body; it’s content inside an attached document. While Proofpoint can still analyze attachments and may extract URLs for analysis depending on configuration and capabilities, the classic “rewrite” mechanism is for body URLs, not attachment-contained links. Previous clicks (B) do not prevent rewriting; rewriting occurs at delivery/processing time. HTTPS hosting (C) does not prevent rewriting; URL Defense supports HTTPS destinations. Whether the email is flagged malicious (D) is not the gating factor for rewriting—rewriting is typically policy-driven (rewrite or not rewrite) to enable time-of-click protection even for URLs that appear benign at delivery. In IR, this distinction matters: phishing in PDFs often requires layered controls (attachment sandboxing, file analysis, and user coaching) because URL rewriting visibility may be reduced.