You may want to call Oregon Department of Revenue directly. This could be a fraudulent mailing and if not, they would be better equipped to answer this question:
Oregon State Department of Revenue Phone: (503) 378-4988 or 1 (800) 356-4222
Reference: http://www.oregon.gov/DOR/contact/Pages/default.aspx
@Lydiadawes You are posting to a very old thread. What specific issue are you having in regard to getting your Oregon refund?