S/MIME
Noun · Security & Infosec
Definitions
Secure/Multipurpose Internet Mail Extensions, a standard for signing and encrypting email messages. It shows up in application security, identity, infrastructure, or incident response work depending on the environment. Teams use the concept to prevent abuse, detect adversary activity earlier, or define stronger control boundaries during engineering, testing, and operations. That makes it operationally important in real deployments.
In plain English: S/MIME is the practical security idea behind a control, weakness, or safeguard. It matters because it changes how attackers succeed or defenders reduce risk.
Example: "During the review, the team focused on S/MIME after telemetry and testing showed it was the fastest way to reduce exposure, tighten controls, and close a realistic attack path before the next production release."