PORTLAND – A letter that was sent from an insurance company but never delivered has been returned to the sender – more than 63 years after it was mailed.

A mail carrier returned the letter two weeks ago to a Congress Street office building that was home to the Maine branch of New York Life in 1943.

When the letter was sent by New York Life, there was no name or address on the envelope, which helps explain why it was never delivered. But it’s unclear where the letter has been hiding all these years.

The letter appears to have been part of a mass mailing, with a brochure encouraging young men to buy insurance and provide for the financial security of their families.

Cullen Fletcher, who manages the Congress Street building where the letter was returned, spotted the mail carrier’s puzzled expression when he attempted to return the errant piece of mail. He then noticed the postmark of Sept. 1, 1943, and the 3-cent postage.

The letter, Fletcher said, may have been the victim of a mechanical malfunction.

“It looked like it got stuck in a machine,” he said, pointing to black scuff marks and the crumpled edge of the envelope.

Portland postal officials were unaware of the letter, which has sparked some curiosity and nostalgia.

Mary McDonough of Portland was a teenager when she worked as a secretary at New York Life’s Portland office when the mailing would have gone out.

The company was bustling at the time and was one of the premier insurers in the region.

“New York Life was No. 1 in the whole country,” said McDonough, 82. “When the agents came to work there, they couldn’t have a side job.”

New York Life still has offices in Portland a block or so away.