Contact the University of Idaho Environmental Health and Safety office at (208) 885-6524.
You should NOT do the following:
Pass the letter or package to others to look at.
Disturb any contents in the letter or package. Handling the letter/package may only spread the substance contained inside and increase the chances of it getting into the air.
Ignore the threat. It must be treated as real until properly evaluated.
Leave the building until instructed to do so.