Mailing and Carrying
Classified Materials

The following procedures apply to mailing or carrying classified materials. These procedures cover the most common circumstances but do not cover the shipment of bulky materials. It is intended as general guidance only and is not a substitute for review of the official regulations.

TOP SECRET material may not be sent through the mail under any circumstances. It must be transmitted by cleared courier or approved electronic means.

SECRET material may be transmitted by U.S. Postal Service registered mail or express mail within and between the United States and its territories. However, the "Waiver of Signature and Indemnity" block on the Express Mail Label 11-B may not be executed, and the use of external (street side) express mail collection boxes is prohibited. SECRET material may be sent through U.S. Postal Service registered mail through Army, Navy, or Air Force Postal Service facilities outside the United States, provided that the information does not at any time pass out of U.S. citizen control and does not pass through a foreign postal system or any foreign inspection. Federal Express may also be used for SECRET material for urgent, overnight delivery only, but contractors must receive approval from their government contracting authority to use this method. 

CONFIDENTIAL material is subject to the same mailing procedures as Secret material, with the following exceptions: 1) CONFIDENTIAL material may be sent by U.S. Certified mail rather than by U.S. Registered mail. 2) Government agencies (but not contractors) may also send CONFIDENTIAL material by First Class mail between and among government agencies only. It cannot be sent to contractors via First Class mail. Under all circumstances, the outer envelope should be marked "Do Not Forward. Return to Sender." Under no circumstances shall the USPS Express Mail label 11-B "Waiver of Signature and Indemnity" be used.

Classified material must be mailed at the post office. Use of street mail collection boxes is prohibited.


All classified material must be double-wrapped with opaque inner and outer covers. It shall be marked as follows:

  • Mark the inner envelope top and bottom on both sides, preferably in red, with the classification in capital letters. A box with classified material should be marked with the classification on all surfaces of the inner wrapping.

  • Write the complete mailing address and complete return address on the inner envelope. The address on the inner envelope should have the name of an appropriately cleared individual.

  • On the outer envelope, write the complete mailing address and return address. Do not indicate on the outer envelope that it contains classified information. Classified mail or shipments should be addressed to the Commander or other head of the organization by title, not by name, or to an approved classified mailing address of a federal activity or to a cleared contractor using the name and classified mailing address of the facility. An individual's name should not appear on the outer envelope. Instead of a person's name, use office code letters, numbers, or phrases in an attention line to aid in internal routing. When necessary to direct material to the attention of a particular individual, put the individual's name on an attention line in the letter of transmittal or on the inner container or wrapper.

For Official Use Only is a document control designation, not a classification. Such material may be mailed in a single envelope.


A receipt identifying the sender, the addressee, and the document should be attached to or enclosed in the inner envelope as noted below. The receipt shall contain no classified information.  It should be signed and returned to the sender.

Top Secret material must be transmitted under a continuous chain of receipts covering each individual who obtains custody.

For Secret material, a classified material receipt must be included with all material transmitted outside the facility.

For Confidential material, a receipt must be included only if the sender deems it necessary, or if the information is being transmitted to a foreign government.

Hand-Carrying Classified Material

For hand-carrying classified material, different procedures apply for surface transportation, commercial air, government air, and for transportation outside the continental U.S.

If you personally transport classified material by car or foot to another location, you must provide reasonable protection for the information under all foreseeable contingencies that might occur while in transit.

Automobile accident, theft and sudden illness are all foreseeable contingencies. This means the classified information must be double wrapped or packaged as though it were being sent by mail, kept under your constant control (i.e., not left in the trunk of your car while you run another errand), and delivered only to an authorized person. A briefcase may serve as the outer wrapper only if it is locked and approved for carrying classified material. Prepare an inventory of the material and leave one copy in your office and another copy with a security officer or other responsible person.


Carrying classified material on trips that involve an overnight stopover is not permitted without advance arrangements for overnight storage in a U.S. Government office or a cleared contractor facility.

For air travel, a written letter of authorization from your security office is required. Your security officer will advise you of appropriate procedures. Stricter procedures are required for air travel outside the United States. For air travel, a locked briefcase may not serve as the outer wrapper.




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