Sam.

An inappropriate usage incident involves misuse of the organization's resources or violations of its acceptable use policies. Sam's actions, where he sends emails to third-party organizations with a spoofed email address of his employer, constitute misuse of the organization's email system and misrepresentation of the organization. This behavior can harm the organization's reputation, violate policy, and potentially lead to legal consequences. Inappropriate usage incidents can range from unauthorized use of systems for personal gain to the dissemination of unapproved content.

References:The Incident Handler (CREST CPTIA) by EC-Council includes discussions on various types of security incidents, emphasizing the importance of addressing and mitigating not just external threats but also internal misuse and policy violations.