Excerpt from USPS notice linked above.

~S~

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What constitutes a "suspicious parcel?"

Some typical characteristics Postal Inspectors have detected over the years, which ought to trigger suspicion, include parcels that:

are unexpected or from someone unfamiliar to you.

are addressed to someone no longer with your organization or are otherwise outdated.

have no return address, or have one that can't be verified as legitimate.

are of unusual weight, given their size, or are lopsided or oddly shaped.

are marked with restrictive endorsements, such as "Personal" or "Confidential."

have protruding wires, strange odors or stains.

show a city or state in the postmark that doesn't match the return address.

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What should I do if I've received a suspicious parcel in the mail?

Do not try to open the parcel!

Isolate the parcel.

Evacuate the immediate area.

Call a Postal Inspector to report that you've received a parcel in the mail that may contain biological or chemical substances.