What is a possible indicator of a suspicious letter or package?

A possible indicator of a suspicious letter or package includes excessive or unusual packaging materials, such as layers of tape or strange odors. Additionally, if the item has no return address, has misspellings in addresses or labels, or is addressed to someone who no longer resides at that location, it may raise red flags. Finally, an unexpected delivery, especially from an unknown sender, can also be a cause for concern.