More than 30 threatening letters, most containing suspicious powder, were sent to financial institutions in eight US states and Washington, D.C, last week, according to USA Today:
http://www.usatoday.com/news/nation/2008-10-21-powder-banks_N.htm
For UK Government advice on how to proactively and reactively manage the risk of biological/chemical threats by post, go to:
http://www.hse.gov.uk/biosafety/diseases/anthrax.htm
If you are concerned about duty of care to employees and would like to turn this advice into concrete procedures for staff mail handling, and you don't have time to do it yourself, contact ARC Consultancy Services to be put in touch with an expert in this field.