WASHINGTON - Post offices and government buildings reopened as the anthrax threat edged into cleanup mode. "This has been one of the most difficult and sad times in postal history," Postmaster General John Potter said yesterday.

A diplomatic mailbag sent from Washington to the U.S. consulate in the Russian city of Yekaterinburg tested positive for what was described as a negligible amount of anthrax spores, consular officials said yesterday. The consulate's mail was tested after a State Department's mail worker in Virginia was diagnosed with anthrax on Oct 25.

In New York, Manhattan Eye, Ear and Throat Hospital reopened yesterday, six days after it was closed by the anthrax threat. Kathy Nguyen, who worked at the primarily outpatient facility, died of anthrax; circumstances of her exposure to the bacterium are still a mystery.

At the Pentagon, officials said there was no indication that anthrax spores found in two postal boxes there had migrated to other parts of the military complex.

The Defense Protective Service checked 150 spots in the Pentagon office, air ducts and air quality and found all negative, spokesman Richard L. McGraw said yesterday.

Kenneth Weaver, the chief postal inspector, told the Postal Board of Governors that his inspectors are screening the mail passing through selected postal facilities and are following up more than 300 leads received from the broadcast "America's Most Wanted."

The focus, he said, is tracking down whoever placed anthrax in the mail.

Potter has estimated that the Postal Service could face increased costs and business losses totaling billions of dollars in the wake of the anthrax attacks.

"Extraordinary expenditures will be required," said Robert Rider, chairman of the Postal Service Board of Governors. "We strongly believe these costs should not be borne by our customers through increased rates,"

Postal chief financial officer Richard Strasser said the costs of adding security, dealing with the terrorists and lost business will total "billions of dollars."

Strasser said the agency has already lost $800 million in reduced business in the eight weeks since Sept. 11. He said it is working to cope with the costs of medical care for postal workers, testing and cleanup of facilities, extra costs for mail handling while the airlines were grounded and changes in postal facilities to increase the security of the mail.

Four people have died of inhaled anthrax since the mail attacks began, including Kathy Nguyen, a New York woman with no apparent connection to the mail or the media or government, which have been the focus of the attacks. Her funeral was Monday.

There was good news Monday for Norma Wallace of Willingboro, N.J., a postal worker who went home from the hospital after a three-week bout with inhaled anthrax.

"I have an obligation to explain that even though we have been confronted with a deadly disease, there is hope," she said.

Wallace is the third inhaled anthrax victim to recover and leave the hospital; three others remain under hospital care. There have also been several cases of the less-severe skin form of the disease.

Washington's giant Brentwood postal facility was closed after anthrax was detected. Contamination has been found in various locations throughout the federal government that received mail from Brentwood. That prompted testing of government mail rooms nationwide.

Most of the Longworth House office building reopened Monday, 10 days after closing in the anthrax threat. The post office in Princeton, N.J., also reopened, and the West Trenton office was to do so yesterday.

Still facing cleanup is the Hart Senate Office Building where Daschle's office is located.

The plan had been to decontaminate the nine-story building with chlorine dioxide gas. Scientists worried that variations in humidity, temperature or the gas itself might prevent uniform performance, and it remained unclear how the building eventually will be cleaned.

In Rochester, Minn., researchers at the Mayo Clinic said Monday they may have a new, faster test for anthrax. Current tests often have false positives and have to be confirmed by more detailed lab testing.

The Mayo Clinic developed a DNA test that promises better results in 30 minutes, instead of days. The test is still experimental, though some laboratories plan to begin using it next week.

In Lansing, Mich., the nation's only manufacturer of an anthrax vaccine said it expects it will be at least mid-December before it can win federal permission to ship it.

BioPort Corp. has been unable to distribute the vaccine since it failed FDA inspections in 1999 and 2000. The company submitted new documents for the FDA's approval last month.

BioPort will start a new production cycle on Nov. 22, spokeswoman Kim Brennan Root said. Inspectors from the U.S. Food and Drug Administration will visit in mid-December, she said.

Back in Washington, authorities were preparing to deal with the piles of mail held since the contamination was reported.

The FBI said sealed containers of congressional mail that were stored in a Washington warehouse are being transferred to another facility in Virginia for inspection. That mail has not been sanitized and thus is being handled as though it is contaminated.

The agency took control of the mail after the Daschle letter was found. It will likely take weeks to inspect and, if necessary, test the 280 55-gallon drums of now-sanitized mail, the agency said.

The Postal Service, meanwhile, has a separate mass of mail addressed to government agencies from its Brentwood facility that was sent to Ohio to be sanitized. Postal inspectors will begin sorting through it within days.

Investigators are looking for letters similar to those sent to Daschle and to news media in New York, hoping to find clues.

"We are just as anxious to resolve this as the American public is, but we want to do this right," said postal inspector Lori Groen.