Letter Returns from 63-Year Disappearance

Thanks again to the folks at New England Anomaly for this tipoff. Well, if all mail was this tenacious, there may be hope yet for stuff I've never received! The other week a letter was returned to the Congress Street office from which it was mailed in 1943. No one know where it's been all this time!!!

Undelivered mail returned to sender 63 years after mailing
April 7, 2007, PORTLAND, Maine
A letter that was sent from an insurance company but never delivered has been returned to the sender -- 63 years after it was mailed. A mail carrier returned the letter two weeks ago to a Congress Street office building that was the 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.
...
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.
...
New York Life still has offices in Portland a block or so away.
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Information from: Portland Press Herald, http://www.pressherald.com
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Photo is from the Antique Mail Room Machines website, titled "Heap of Papers," (Denver, CO, photograph by Harry M. Rhoads, 1880/81-1975)