With letters contaminated by anthrax arriving at offices in New York, Nevada and Washington, D.C., mailrooms and delivery services across the country are implementing new procedures to protect workers.

U.S. Capitol Police Lt. Dan Nichols said mail delivery to lawmakers would be halted indefinitely after sophisticated tests confirmed Tuesday that a letter mailed to the office of Senate Majority Leader Tom Daschle did contain anthrax.

In California, Gov. Gray Davis ordered state employees to stop handling mail until they complete training sessions on how to deal with items suspected of containing chemical or biological contaminants.

"People are lining up around the block to take them," said Anne DaVigo, a spokeswoman for the California Highway Patrol, which led the training sessions.

On Monday, Davis released an instructional videotape made at the CHP sessions. Any Californian can request a copy or watch it online, Davis said.

Elsewhere, mailroom employees were being warned to check packages for misspellings in common names and words, look for powdery substances and incorrect postage and contact authorities about suspicious mail.

The Postal Service announced the creation of a task force to examine mail security and hazardous-material safeguards. The Centers for Disease Control and Prevention issued guidelines for handling letters and packages. And private delivery companies were scrutinizing their own procedures.

At NBC studios in New York, where one employee contracted the skin form of anthrax and another has shown symptoms, the network has stopped accepting mail from the Postal Service.

New York Mayor Rudolph Giuliani said that city officials received almost 100 calls about suspect mail by midday Monday and that 24 packages had been recovered for investigation. He said Tuesday that no anthrax had been detected in the initial tests.

At a meeting of the National Postal Forum in Denver, Postmaster General Jack Potter told participants that the U.S. mail is safe.

"We cannot afford for that confidence to erode," Potter told representatives of corporate and government mailrooms. "With additional vigilance and additional work with our public, we won't let that happen."

A mail-sorting facility in Florida was shut down Monday after a small amount of anthrax spores was found. The office handled mail for American Media Inc., where an editor died from a respiratory anthrax infection. The processing area reopened Tuesday after it was cleaned by federal environmental workers.

FedEx Corp. employees were put on higher alert for suspicious mail. The company is carefully screening packages and called the FBI about a few suspicious items, all of which turned out to be false alarms. It also is advising making gloves and respirators available to employees.

In Washington, White House spokeswoman Anne Womack said mailroom security procedures also had been enhanced. She would not give details.

News organizations across the country said the same.

CBS spokesman Dana McClintock said even mail marked `confidential' will be opened by mailroom staff after notifying the recipient. "Junk mail is being set aside for the time being while we streamline the process," he said.

The CDC and Potter, the postmaster general, urged people to watch for letters or packages that lack a return address or have a vague address. Potter said suspicious pieces of mail should be put in a plastic bag and turned over to authorities.

"Don't open it," he said. "Don't shake it. Don't smell it."