First anthrax, now ricin; like there aren't enough things for mail sorters and carriers to worry about. This story in the NYTimes, Powder Found in Senate Leader's Office Confirmed as Poison, describes the latest poison-mail incident on the US Capitol.
It's only a matter of time before this extensively open system (which, I found out last time I was at Dulles, has been closed modestly: there are no blue mail boxes, not sure whether it's because of bombs or poison -- probably bombs) is closed down for public safety reasons. Of course, there is a digital identity application here in the form of a need to slip a credential card into a mail receptical before putting the mail/parcel in. The machine would then record the depositor's identity for future tracing requirements. How the civil right to private and unimpinged communication would be addressed is another matter.
Interesting to note that, at least to my untrained, anecdotal view, the story of poisoned mail on the Capitol is receiving less media time this go round.