This detection rule targets messages that contain a single link from the domain 'breely.com', specifically when the link is masquerading as a PDF document. The primary intent behind this tactic is to redirect users to a different, potentially malicious website under the guise of a legitimate PDF file. The detection is triggered when an inbound message contains exactly one Breely link and includes an analysis of the link's display text to confirm it claims to be a PDF. This behavior is often associated with Business Email Compromise (BEC) and credential phishing attacks, exploiting trust through social engineering techniques. The rule employs content and URL analysis methods to identify such anomalies in message links.