The Postal Service™ is reminding customers that metallic mercury and devices containing metallic mercury are always prohibited in the mail stream. This includes antique items such as thermometers, barometers, blood pressure monitors, and similar devices.

Lithium batteries (like the ones in cell phones, laptops, and electronics) pose significant risks of catching fire. Lithium batteries are mailable within certain guidelines; see domestic and international shipping restrictions.

HAZMAT Search Tool

Many common household products contain hazardous materials (HAZMAT, or dangerous goods [DG] when shipped internationally). These items could cause injuries or damage if not properly prepared for mailing.

Assess: Is it HAZMAT?
Type your item's proper shipping name, ID Number, or description into the HAZMAT Search Tool. (Note that the tool is looking for very specific terms.)
Check: Can I ship it?
Your item's results will show whether it is mailable or prohibited for air, surface, and international shipping. If your item is prohibited, you can't send it with USPS and need to find another solution.
Determine: How should I package it?
There are specific guidelines you must follow when shipping mailable HAZMAT/DG. In the search results, select the link to see the USPS™ Packaging Instructions for your item, which includes quantity limits and packaging and labeling requirements.
Act: Ship your item.
After following all USPS Packaging Instructions for your item, you can ship your package at a Post Office™ location (or use Click-N-Ship® service and Schedule a Pickup). Please separate HAZMAT packages from all other packages and present them in a container marked "HAZMAT."