Mailability decisions are based on Postal Service statutes and regulations in effect at the time the ruling is issued. Over time, some rulings may become obsolete or require modification to conform to changes in applicable laws and regulations. When rulings are issued, the requirements of other governmental agencies (e.g., U.S. Department of Transportation, Centers for Disease Control and Prevention) may be taken into consideration to the extent that they are consistent with Postal Service policy and authority.
Requests for rulings must contain specific items of critical information appropriate to the category of the material, as noted in 215.2 and 215.3 and DMM 601.10.6.
Acceptability for mailing hazardous materials depends on many factors, such as the container fluid/vapor capacities, the ability of the complete mailpiece to contain the material, and the method of absorbing and containing the material in case of accidental leakage of the primary receptacle.
To determine mailability of a specific material, a mailer must submit a material safety data sheet (MSDS) (see Appendix D) and the following information to the PCSC:
- Common and proper shipping name of the material, hazard class, and the assigned United Nations (UN) or North American (NA) identification number.
- Chemical composition by percentage of weight.
- Toxic properties.
- Irritant action when inhaled, swallowed, or with contact to skin or eyes.
- Special precautions necessary to permit handling without harm to USPS employees or damage to property or other mail.
- Explanation of warning labels and shipping papers required by local, state, or federal regulations.
- Description of the proposed packaging method, including the addressing, required markings, and documentation.
- Volume of material per mailpiece, proposed number of pieces to be mailed, class of mail, and post office(s) of mailing.
The hazards present with chemicals and other types of hazardous materials may not be readily apparent. Materials classified under one hazard class can present additional or subsidiary hazards more commonly associated with a different hazard class. For example, swimming pool chemicals may cause fires or release poisonous fumes or be corrosive or poisonous. Therefore, it is essential when determining mailability to correctly identify the material based on the mailer–supplied documentation (i.e., the MSDS and other information) and never to assume a general designation using unsubstantiated information.
To obtain a ruling on the mailability of restricted or perishable matter, a mailer should provide the mailing office with following:
- Detailed description of the restricted or perishable matter.
- Special precautions necessary to permit handling without harm to Postal Service employees or damage to property.
- Proposed method of packaging.
- Explanation of any local, state, or federal regulations that apply to shipping such matter.
- Quantity per mailpiece and per mailing, frequency of mailing, and post office(s) of mailing.
When information about restricted or perishable matter is insufficient to make a mailability determination, or when there is doubt about the mailability of a particular item, contact the PCSC.