http://www.state.il.us/court/opinions/supremecourt/1997/october/opinions/html/81920.txt said:
Based upon experience and
drug-trafficking intelligence, the United States Postal Inspection Service has
developed a drug package profile for packages deposited in the Express Mail and
Priority Mail. Profile characteristics include: (1) heavy brown paper wrapping; (2)
heavily taped seams; (3) handwritten address label; (4) sent from one individual
to another; (5) mailed from a zip code different from the address; and (6) a
fictitious address. While it is uncertain whether any one of these criteria, standing
alone, would support a finding of reasonable articulable suspicion, in various
combinations these criteria might indeed support such a finding.
...
According
to the Postal Service, only 5% of Express Mail packages are addressed from one
individual to another. This fact, in concert with the brown paper and heavy taping
typically used to prevent narcotics odors from escaping such packages, warranted
a minimally intrusive detention and investigation of defendants package under the
reasonable articulable suspicion standard. United States v. Place, 462 U.S. at 703,
77 L. Ed. 2d at 118, 103 S. Ct. at 2642.