FORT WAYNE, Ind. (WOWO): After the threat of losing Saturday delivery, now door-to-door mail delivery could be a thing of the past. A new proposal could mean that the US Postal Service will switch from door-to-door delivery to curbside and neighborhood cluster boxes, that according to our partners in news at 21 Alive. The new plan is designed to cut costs by up to 4.5 billion dollars a year, and would affect about 37 million residences and businesses.