I was surprised to find this on page 66 of the IEEE Computer (April 1995), but suddenly it seems so topical.

Be Alert: Letters or Packages Can Be Lethal

Personal communication are increasingly electronic these days, thanks to e-mail, but while e-mail is more immediate, old-fashioned postal mail is more dangerous. Letter and package bombs are becoming more sophisticated, as a recent Wall Street Journal article pointed out, and with sophistication comes increase chance of injury or death. The serial bomber known as Unabomber, whos most recent letter bomb killed a Young & Rubicam advertising executive in December, is still on the loose, and his devices indeed show increase skill. The bomber's motivation is not known, but his targets have chiefly been computer-and airline related. Of particular concern is that several of his targets have been [IEEE] Computer Societer members or associates. To protect yourself, you family, and colleagues, be aware of the following guidelines issued by the Federal Bureau of Investigation:

When out of the country, never accept mail, especially packages, at your foreign quarters.
Make sure family members and clerical staff know to refuse all unexpected mail at home or office.
If in doubt, treat the item as suspect: it might be a bomb.

Possible clues to letter and package bombs:

Excessive postage
Excessive weight
No return address
Incorrect titles
Titles but no names
Misspellings or erratic typing
Restrictive markings such as Confidential or Personal
Foreign mail, air mail, and special delivery
Lopsided or uneven envelope
Protruding wires or tinfoil
Visual distractions
Oily stains or discolorations
Excessive securing material such as masking tape or string
Rigid envelope

If a suspicious letter or package arrives, do not touch it. Instead, immediate call your local [RCMP] FBI office, police or fire department, or the FBI's Explosives Unit and Bomb Data Center at (202) 324-2696.

Amit Parghi (parghi@BanffCentre.AB.CA) pointed out:

Unabomer's style "doesn't fall into many of these categories. It's usually mailed from the Bay Area or Sacramento, is meticulously wrapped and finished (he reportedly polishes the finished bomb casings) and is sent via the postal service. Plus his latest strike was on Monday [4/24/95] in Sacramento ... The FBI have set up a Unabomer hotline and a US$1 million reward. Plus he sent out three letters coinciding with this latest attack ... very strange."

The Federal Bureau of Investigation has information on the Unabomber and the Oaklahoma City Bombing at http://www.fbi.gov/

This is http://www.cs.ubc.ca/spider/harrison/bomb-warning.html.
Maintained by Jason Harrison (harrison@cs.ubc.ca). Last modified: Thu Aug 24 11:58:52 1995.