The United States Postal Service has reversed course and announced that 3,563 rural post offices nationwide — including 30 targeted for study in Maine — will stay open.

In a statement released early Wednesday afternoon, Postmaster General Patrick Donahoe announced a new strategy — which should be completed by September 2014 — to keep existing post offices, no matter how small, open, but with modified retail window service hours to match peak customer use.

“This is a victory for mail service in rural Maine and across the country,” Sen. Susan Collins said in an email Wednesday afternoon. “There should be clear minimum standards for service — which we establish in the bill just passed through the Senate — and communities should have a real voice in the decisions.”

As part of the new USPS cost-saving strategy, access to post office retail lobbies and P.O. boxes would be unchanged.

Last July, the U.S. Postal Service said it was considering closing about 3,200 post offices, including 34 in Maine. That number was cut by four shortly after it was determined that customers served by offices in Matinicus, Stoneham, Topsfield and West Forks would lose regular and effective mail service.

Donahoe said under the new USPS plan, about 13,000 post offices will have work hours reduced, be co-located with a nearby business such as the local pharmacy or merged with another location. Other options include providing service to residents and businesses in the affected community by rural carrier or highway contract route or offering service from a nearby post office.

“There are 244 post offices in Maine that will be affected by this new policy. No hours of service will change at any post office until the community meetings and surveys occur after Labor Day,” said Collins.

The new plan will be reviewed by the Postal Regulatory Commission. After that, community meetings will be held in all areas affected by modified post office hours.

“Community meetings and surveys will be conducted to review the options in greater detail,” said Tom Rizzo, USPS spokesman for the Northern New England District.

“Communities will be notified by mail of the date, time and location of these meetings.”

The USPS, which estimates this cost-saving strategy will save approximately a half billion dollars each year, also is going to offer a voluntary early retirement program for its 21,000-plus nonexecutive postmasters.

“To reduce the impact on existing employees, the Postal Service is offering financial incentive to select postmasters and they have until June 22 to accept the offer and either retire or leave by July 31,” said Rizzo.

Rep. Mike Michaud said in a statement that he was encouraged by Wednesday’s USPS announcement.

“The Postal Service must be put on a path to long-term sustainability, but that future cannot be balanced on the backs of the many rural communities that are dependent on quality mail service,” Michaud said. “I will continue to fight to ensure that the USPS honors its commitment to universal service.”

“I am pleased to see that Postmaster General Donahoe has reconsidered his ill-advised plan to close thousands of rural postal offices, including 34 in Maine, and instead focus on alternative strategies to ensure these critical links to our nation’s communities stay open, either with reduced hours or through co-location with other businesses,” said Sen. Olympia Snowe.

Collins also said she is hopeful the postmaster general soon will announce a new plan regarding proposed consolidations of 183 processing and distribution plants nationwide beginning May 15. One of those plants is the Eastern Maine Processing and Distribution Center in Hampden, which has been targeted to have its processing duties shifted south to Scarborough, causing the loss of 170 jobs at the plant.

“He will make an announcement about postal plants next Thursday,” said Collins, who authored a provision in the Senate bill passed 62-37 two weeks ago mandating certain overnight delivery standards in some areas, which would keep many of the processing facilities open. “The Hampden plant could not be closed if those standards become law. I have urged the postmaster general to allow the legislative process more time.”