Here's the problem: after the 2001 anthrax scare, all mail sent to Congress has become incredibly delayed (on the order of weeks) while it gets tested and radiated. What some lobbying campaigns have done to get around this is send mass faxes to congressional offices overnight. It's like having access to someone else's office printer and that person has 1/538th of control over the federal government.

The takeaway is, unless these letters are hand delivered, I doubt theyll reach their intended recipients in time.