Some mail devices may be recognized by visual inspection. Mail handling personnel should be alert to a number of recognition clues, the most common of which are detailed below.

Place of origin: Note the postmark. This may be from a country directing a terrorist campaign or from an area associated with postal bombs. If the arrival of such mail is uncommon, it should be treated as suspect.

Sender's Writing: Mail should be treated with caution if it features a foreign style of writing not normally received, on the address. This should be considered in relation to No. 1 above.

Excessive Postage: Mail with excessive postage and no return address should be viewed with caution. Additionally, mail bearing a postage cancellation stamp that does not match the return address should also raise one's suspicion.

Balance: A letter or package should be treated as suspect if it is unbalanced, has loose contents, or is heavier on one side than the other.

Weight: If a package or letter seems excessively heavy for its volume, it should be treated as suspect.

Feel: If an envelope has any feeling of springiness at the top, bottom, or sides, but does not bend or flex, be careful, this is a key sign of an explosive device. Warning - examine mail gently!

Protruding wires: Mail devices are often loosened or damaged by rough handling. It is possible that a fuse, electrical wire, or connection may become loose and penetrate the wrapping or envelope. Any such device is unstable and highly dangerous. It must not be touched.

Holes in the Envelop or Wrapping: An explosive mail device that has been handled roughly may show wire or spring holes in its outer wrapping. This, by itself or in combination with the other clues described, should alert mail handlers to a suspect device.

Grease marks: Certain types of explosives or hazards leave greasy black marks, oily stains, discolorations or crystallization on the envelope; all good indications of a suspect device. It can also mean that the explosive device has become old and unstable, making it extremely dangerous.

Smell: A smell suggestive of almonds or marzipan, or any other strange odor, is an indication of a suspect device.

Unrequested Deliveries: Unrequested deliveries, especially packages, should be screened and treated with caution. A book or thick brochure discovered upon opening a delivery should be reported to the security department or examined for any of the above clues. Any mail which raises the slightest suspicion should not be handled. Remember the catch phrase: TOUCHING TRIGGERS TRAGEDY. (It is of benefit to both parties if senders place their name, organization address, and telephone number on packets. Then, in cases of suspicion, they may be contacted for an explanation of the contents.)

Suspicious Packaging: If an envelope is taped down all around, instead of having a normal opening flap, it may contain a booby trap spring. Such letters should be handled very carefully and treated as suspect.

Letter Stiffness: Gentle handling can reveal whether an envelope contains folder paper or a device. The presence of stiff cardboard, metal or plastic should alert the handler to a possible suspect device.

Inner Enclosures: If, after opening a letter or package, the mail handler encounters an inner sealed enclosure - whether or not it fits any of the above descriptions-the item should be treated as suspect.

Warning: All of the above are only possible indicators for field expedient assessment and recognition of a letter bomb or parcel containing a chemical or biological hazard. Their presence or absence neither confirms nor eliminates a potential threat.

For additional information, please visit http://www.usps.com/websites/depart/inspect/bombcorp.htm