Police say white powder sent in envelopes to the Wall Street Journal building in New York was harmless and probably was flour.
Harvard Law School, where similar mail was received, also said state police tests found it not to be a hazard.
The envelopes bore postmarks from Knoxville, Tenn., and contained a blank piece of paper with the powder.
The envelope sent to Harvard Law School was opened by a secretary to professor Alan Dershowitz. The fifth floor of the building was sealed off as a precaution.
Dershowitz recently wrote an opinion piece in the Wall Street Journal defending Israel's actions in Gaza.
An FBI spokeswoman in Boston said about seven other suspicious envelopes received elsewhere in Massachusetts are believed unrelated to the Harvard and Wall Street Journal mail.
The town hall in Rockland was briefly evacuated when several suspicious envelopes addressed to selectmen were received there.
This program aired on January 21, 2009. The audio for this program is not available.