Final answer:
USPS does not mandate a specific statement to be placed on the outer wrapper of First Class Mail containing confidential information. Senders may voluntarily mark packages as 'Confidential' and should use services like Certified Mail for sensitive contents. Regulations can vary for government and sensitive business documents, with additional security measures possibly being applied.
Step-by-step explanation:
When transmitting confidential information via the United States Postal Service (USPS) First Class Mail, there is no specific statement required by USPS regulations to be placed on the outer wrapper to denote the contents as confidential. However, in certain cases, senders might add a marking such as 'Confidential' to alert the recipient to the sensitive nature of the contents, but this is a best practice measure rather than a USPS requirement. It is essential to use an appropriate mailing service like Certified Mail or Registered Mail for added security, receipts, and tracking capabilities if the information is sensitive. In some instances, the sender may also include a statement discouraging unauthorized individuals from opening the mail if it's not addressed to them, but this also is not mandated by the USPS.
Additionally, it should be noted that when mailing sensitive government or business documents, specific procedures and regulations often apply, which may require different handling or labeling protocols. Organizations such as the FBI or USPS, especially when dealing with biosecurity risks, may use additional safety measures such as x-ray irradiation to ensure the safety of mail handling.