A security architect is implementing a new email architecture for a company.

S/MIME (Secure/Multipurpose Internet Mail Extensions) is a protocol that enables secure email messages to be sent and received. It provides email encryption, as well as digital signatures, which can be used to verify the authenticity of the sender. S/MIME can be used with a variety of email protocols, including POP and IMAP.

References:

https://www.comptia.org/content/guides/what-is-smime

CompTIA Security+ Study Guide, Sixth Edition (SY0-601), page 139