Full responsibility rests with the mailer to comply with all Postal Service and non-Postal Service laws and regulations when mailing hazardous material.
Anyone who mails, or causes to be mailed, a nonmailable or improperly packaged hazardous material may be subject to legal penalties (i.e., fines and/or imprisonment), including but not limited to those specified in 18 U.S.C. Transporting hazardous materials before entry as U.S. Mail and after receipt from the Postal Service is subject to DOT regulations.
Mailers must identify whether a shipment contains hazardous materials when generating the label, including Postal Service-generated labels (e.g., from USPS Application Programming Interfaces (API), Click-N-Ship, or Merchant Returns Application).
The mailer is responsible for accurately identifying the flashpoint, toxicity, corrosive, or any other hazardous properties before determining mailability.
A Service Type Code (STC) is a three-digit code that identifies the type of product or service used for a Postal Service package and designates the contents as hazardous materials. Mailers are required to use a unique STC within the Intelligent Mail package barcode (IMpb) and the Intelligent Mail matrix barcode (IMmb) for each domestic outbound and return package that contains hazardous materials, regardless of whether the mail is entered at origin or destination -except for packages destined for Army Post Office, Fleet Post Office, and Diplomatic Post Office (APO/FPO/DPO) locations, U.S. Possessions, Territories, and Freely Associated States (FAS), excluding Puerto Rico. The STC must correspond to the product being shipped.
Mailers must also use the STC that indicates the product and extra service if they purchase an eligible extra service. However, combining multiple extra services (e.g., signature confirmation and insurance less than or equal to $500) is prohibited when mailing hazardous materials.
A full list of HAZMAT STCs can be found in Appendix G and Publication 199.
Mailers tendering packages that contain hazardous materials to the Postal Service must use Extra Service Code (ESC) 857. Mailers tendering domestic packages may optionally use one of 23 unique content-specific ESC for outbound and return packages that corresponds to the specific category of hazardous material contained within the mailpiece. If one of the content-specific ESC is used, then ESC 857 may be omitted when not enough extra-service code fields are available for the package details.
A full list of ESCs can be found in Appendix G and Publication 199.
Note: While using the content-specific ESC is currently a recommended practice, the Postal Service may make this requirement mandatory in the future.
Mailers shipping hazardous materials domestically utilizing PC Postage or USPS Ship platforms must incorporate the applicable STC and/or ESC listed in Appendix G and Publication 199 and transmit a Shipping Services File (SSF), using Version 1.7 or higher, or Shipping Partner Event File (SPEF), using Version 5.0 or higher, to the Postal Service before, or concurrent with tendering any hazardous materials shipments.
In cases where legacy postage meters or hard-copy postage forms are used, mailers must present hazardous materials shipments directly at a Postal Service retail or business mail entry unit.
