Mailability decisions are based on Postal Service policies in effect at the time of the ruling. Rulings may consider other governmental agency standards, provided they align with Postal Service policies and authority. Some rulings may become obsolete or require modification to conform to changes in applicable laws and regulations.
Requests for rulings must contain specific items of critical information appropriate to the category of the material, as noted in 215.2, 215.3, and 324.
Acceptability for mailing hazardous materials depends on many factors, such as the container fluid or vapor capacities, the ability of the mailpiece to fully contain the material, and its capacity to absorb and contain the material in case of leakage.
To determine mailability, mailers must provide a Safety Data Sheet (SDS), formerly known as Material Safety Data Sheet (MSDS), along with detailed information about the material to the Post Office or acceptance facility. This includes chemical composition, hazards, packaging, and other relevant details. If information is insufficient to determine mailability or if the item’s mailability is uncertain, mailers may submit an SDS and the following information to Product Classification (refer to 214 for contact information) or the PCSC (refer to 213 for contact information):
- 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.
- Flashpoint.
- 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.
Hazards associated with chemicals and other hazardous materials may not be immediately evident. Materials classified under one hazard class can pose additional risks typically linked to a different hazard class (e.g., swimming pool chemicals may cause fires, release poisonous fumes, or be corrosive or toxic). Therefore, determining mailability requires an accurate identification of the material based on mailer-supplied documentation (i.e., the SDS and additional information), and general designations should not be assumed without verified information.
To determine mailability, mailers must provide detailed information about the matter to the Post Office or acceptance facility. This includes hazards (if applicable), packaging, and other relevant details. If information is insufficient to determine mailability or if the item‘s mailability is uncertain, mailers may contact Product Classification (refer to 214 for contact information) or the PCSC (refer to 213 for contact information):
- 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.
