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.
All USPS Marketing Mail parcels must bear an Intelligent Mail package barcode (IMpb) prepared under 204.2.0. USPS Marketing Mail parcels may optionally use an IMb in lieu of an IMpb when they are presorted and containerized in 5-digit sacks or other approved containers prepared to the 5-digit level, provided each parcel bears a unique IMb that cannot be reused for 45 days. In situations where the IMb is used in lieu of the IMpb, a Mail.dat or Mail.XML file will be accepted in lieu of a Shipping Service File.