Under a cost-saving plan by the U.S. Postal Service, millions of Americans accustomed to getting their mail delivered to their doors will have to trek to the curb and residents of new homes will use neighborhood mailbox clusters, the agency said Tuesday.

Sally Davidow, spokeswoman for the American Postal Workers Union, said that moving to cluster delivery would put the Postal Service at a competitive disadvantage against its main competitors, FedEx and UPS , which continue to deliver at the door.

When was the last time you mailed a letter to your son, daughter, mother, father or friend?