Which one of the following is a definition of CEM?

The correct definition of CEM within the context of telecommunications and networking is best represented by "Centralized Email Management." This term refers to systems or tools designed to manage, organize, and control email communications centrally, making it easier for organizations to handle their email traffic efficiently.

Centralized Email Management involves ensuring security measures are in place, streamlining email processes, and enhancing productivity by managing the flow of both incoming and outgoing emails from a single platform or system. This can include filtering spam, ensuring compliance with regulations, and maintaining an archive of communications for retrieval.

While the other options represent various technologies or concepts, they do not align with the established terminology of CEM in the telecommunications space. Cable Ethernet Module, Computer Error Monitor, and Phone Modem are all distinct components or concepts in the field but do not pertain to the centralized management of emails.