Amazon.com Inc. has reached a new agreement with the U.S. Postal Service, providing a lifeline to the beleaguered government agency and securing delivery for customers in rural America. Under the deal, Amazon will retain about 80% of its existing deliveries with the Postal Service, or more than ‌1 ⁠billion packages per year, according to a person familiar with the matter. “We’re pleased to have reached a new agreement with USPS that ⁠furthers our longstanding partnership and will let us continue supporting ⁠our customers and communities together,” Amazon spokesperson Terrence Clark said in a statement. The Postal Service did not immediately respond to a request for comment. Securing a deal with Amazon ensures that the Postal Service maintains most of the business from its largest customer, a safety net for the agency as it seeks to stem heavy financial losses year after year. Financial terms of the agreement, which was earlier reported by Reuters, were not immediately available. Shoring up the mail carrier’s finances is a critical priority for Postmaster General David Steiner, who has warned …