System Administrator Government off-the-Shelf Applications (SAGA) Practice Exam

The key idea here is authenticity and confidentiality of email through digital signatures and encryption. Digitally-signed email uses a private key to attach a signature to the message, allowing recipients to verify who sent it and that it hasn’t been altered. Signed/encrypted email goes a step further by also encrypting the message content so only the intended recipient can read it. The described capability—delivering such secure messages to individual mailboxes, group mailboxes, and mail-enabled shared folders on any enterprise mail platform—maps exactly to enabling digitally-signed or signed/encrypted email.

Plain text email has no signatures or encryption, so it doesn’t match the capability. Attaching only files isn’t about signing or encrypting the email itself. Unsigned email explicitly lacks a signature, which is why it isn’t correct either.