If I had a reason to be paranoid how long should I write return to sender on the package and let it sit in my house before it's safe to open? Before anyone says that it has to be a CD.... it doesn't. They can find drugs in the package, deliver them to your mailbox, then just raid after you pick up your mail.
Example A of that:
Anyone know?
I recommend waiting 1-2 years, just to be on the safe side.