http://www.bt.cdc.gov/agent/anthrax/mail/suspiciouspackages.asp
Centers for Disease Control and Prevention, U.S. Department of Health and Human Services
Between September and October 2001, several letters containing Bacillus anthracis were sent through the mail in several areas of the United States. Although there have been no recent mail-related anthrax exposures, all persons should take appropriate steps to protect themselves and others from exposure to Bacillus anthracis by following these guidelines for recognizing and handling suspicious packages.