The Mailmen on the route must have been Psychic if they delivered this letter correctly. It's addressed to "Boston, RI" with no street address.

Actually, there wouldn't have been any problem with delivery of this letter, as it is addressed to Chase & Sanborn the famous coffee makers. Caleb Chase and James Sanborn were the first coffee makers to sell ground coffee in a can in 1879.  The Company's original base was in Boston, Massachusetts and later spread to include Chicago and Montreal. The company was later brought by Nestles  and just recently was acquired along with MJB and Mills Brothers by Sarah Lee.