The cash-strapped U.S. Postal Service said yesterday that it will raise postage rates on Jan. 27, including a 1-cent increase in the cost of first-class mail to 46 cents, The Associated Press reported yesterday. It also will introduce a new global "forever" stamp, allowing customers to mail first-class letters anywhere in the world for $1.10. The post office, which expects to lose a record $15 billion this year, has asked Congress to give it new authority to raise prices by 5 cents, but lawmakers have failed to act. The mail agency will also increase rates on its shipping services, such as priority mail, by an average of 4 percent. The post office, which is struggling with debt and low cash flow, said the rate hikes were partly aimed at bringing in new revenue while maintaining its pricing advantage in the shipping business. Earlier this year, it was forced to default on two payments due to the Treasury totaling $11.1 billion for future retiree health benefits because it lacked sufficient cash reserves.