The U.S. Postal Service receives a dozen or so reports of letter or package bombs a year and says there are some signs to look for to avoid danger.
A mail bomb can be in either an envelope or parcel, but among the possible tip-offs are these:-Special instructions such as "personal" or "private" or other notations such as "rush" or "fragile" when such an endorsement might be considered unusual.
-An addressee's name misspelled or an incorrect title.
-No return address or one that doesn't coincide with the postmark.
-Protruding wires, aluminum foil, oil stains or a peculiar odor.
-Envelopes with rigid, lopsided appearance, or poorly wrapped, irregular shaped packages with soft spots or bulges.
-Ticking, buzzing or sloshing sounds.
The U.S. Postal Service advises that if a suspicious letter or package is observed, leave the area and call for assistance.