When transmitting Secret information in a U.S. national security / classified context, several specific handling and mailing requirements apply, especially when using U.S. Postal Service and commercial carriers.

Direct answer (core test-style points)

For the common question “What requirements apply when transmitting Secret information? (Select all that apply)” regarding USPS Express Mail options, the correct requirements are:

  • External street-side collection boxes are prohibited when transmitting via USPS Express Mail.
  • The Waiver of Signature and Indemnity block can never be selected for U.S. Express Mail.

These two are the “select all that apply” correct answers in that multiple‑choice formulation.

Why those requirements exist

  • Secret material must remain under continuous positive control until delivered; dropping it in an unattended street‑side box breaks that control and increases interception risk.
  • Requiring a signature on delivery creates a tracked custody chain; allowing a waiver of signature removes that control, so the waiver option is forbidden for Secret shipments.

In many training and quiz contexts, the other options (“registered mail receipt is always required” and “USPS registered mail is never permitted”) are not the correct choices for that specific Express Mail question, even though registered services can be used in other classified‑mail scenarios according to separate policy.

Broader secure‑transmission expectations

Beyond that specific USPS Express Mail question, transmitting Secret or other highly sensitive information generally also involves:

  • Using encrypted channels (e.g., VPN, TLS, secure email) so the data cannot be read in transit.
  • Restricting access to those with both a valid clearance and a need‑to‑know.
  • Maintaining audit trails of who sent, received, and accessed the information.
  • Following detailed rules for packaging, addressing, and documenting classified material during transport, plus using approved facilities and procedures at each end.

Information gathered from public forums or data available on the internet and portrayed here.

TL;DR: For the specific “what requirements apply when transmitting Secret information via USPS Express Mail” quiz‑style question, select:

  1. External street‑side collection boxes are prohibited, and
  2. The Waiver of Signature and Indemnity block can never be selected.