US Postal Service
Information from the United States Postal Service (USPS) about Handling and Processing Mail Safely.
Screen all mail and packages for suspicious items when they first arrive at your mailroom for sorting. Staff who sort mail by hand should perform the screening, as they are the ones most likely to notice a suspicious item. Unfortunately, screening procedures for incoming mail and packages are not foolproof. The person who first detects a suspicious letter or package is often not the intended recipient.
Prominently display a list of suspicious letter and package indicators in your mailroom and provide a copy of the list to all staff to ensure they’re familiar with it. The Postal Inspection Service’s Poster 84, Suspicious Mail or Packages, illustrates key characteristics of a suspicious or potentially dangerous mail item.