USPS: Hazardous Materials (HAZMAT)
Send hazardous materials with USPS
The USPS requires that you specify when a shipment contains any material or substance, such as chemicals or flammable items, that may injure people or cause damage when not handled properly.
This article will guide you through how to specify that your USPS shipment contains hazardous materials.
Before We Begin
Postsale supports shipping hazardous materials (HAZMAT) with USPS. This article assumes that you have at least one USPS account connected to Postsale.
When shipping Hazardous materials, the USPS supports:
- Domestic shipments only
- The following USPS services:
- USPS Ground Advantage®
- USPS Priority Mail®
- USPS Priority Mail Express®
Specify the Shipment Contains Hazardous Materials
Configuring a shipment for a package that contains hazardous materials is similar to configuring any other shipment in Postsale:
- Verify that the correct carrier and service are selected.
- Enter the correct weight and dimensions for the package.
- Configure any additional options.
Then, specify that the shipment contains hazardous materials:
Expand the Package section in the Dock.
Check the Contains Hazardous Materials option.
Select the type of hazardous material contained in the package from the Hazardous materials type drop-down menu.

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