A letter or package which, based upon its physical characteristics, may lead a person to suspect it contains explosives or some other hazardous substance. Characteristics that may raise suspicion include letters and packages with:

• No return address.
• Misspelled names and address.
• Excessive packaging or tape.
• Oily stains; unusual odors.
• Indications of wiring.
• Foreign postmark.
• Noise coming from inside.
• Powdery substance falling out.
• Liquid leaking out.

None of these factors alone or together are a sure sign that a package or letter is dangerous. The above listed signs may serve to raise your level of suspicion and merit precautionary measures such as wearing gloves and a mask when handling the item or making a notification to 911.