Michele Leonardi holds a postcard postmarked 1946 and just delivered last week in University Park, Md. (Bill O'Leary/The Washington Post)

It didn’t make sense, but there it was: A postcard was sticking out of the stack of mail Michele Leonardi had pulled from her mailbox on the first day of March. On it was a 1 cent stamp and a 1946 postmark.

“I didn’t believe what I thought I was seeing,” she said.

The address was for her home in University Park in Prince George’s County, but the name was unfamiliar. She couldn’t help but wonder where had the postcard been for the last 68 years.

Two days later, a second postcard slipped out of Leonardi’s rubber-band-bound mail. Same sender (Mame, Doc, Mele and Leo), same intended recipient (Mr. and Mrs. Calvin Beach), same year (1946).

Was someone playing a joke? Had the Postal Service found an old bin of mail and decided to deliver it? Fortunately, the post office didn’t ask for postage due; postcards now cost 34 cents to mail.

About 40 miles away, in Pikesville in Baltimore County, Wanda Beach, 89, was likely wondering how her sister Mele Pasela, now 91, would react to the surprise she had sent her. Last month, while wading through some old storage boxes containing letters her husband, Calvin, had sent to her when he served in World War II, Beach stumbled across two postcards sent by her sisters and brother-in-laws during a winter vacation in Miami.

“Really is like heaven here,” wrote Pasela.

In five short sentences, using the lost art of postcard writing, Pasela shared with her sister what the two couples had done and what their plans were for the week.

“Arrived 3 hrs. late last nite but had a good time on the train. Spent all afternoon sightseeing. Miami Beach was crowded with bathers. Expect to go bathing during the week.”

Beach thought her sister would “get a kick” out of seeing the postcards again: One had ducks swimming in a lake at a “peaceful retreat in tropical Florida.” and the other was of Jimmie’s on the Trail, a popular Miami club in the 1940s that featured live music and variety acts.

Beach placed the cards in an envelope and mailed them to her sister, who now lives in Florida.

Instead of reaching Pasela’s home, the cards turned up, one at a time, at Leonardi’s address, where Beach and her husband rented their first apartment.

Soon after, Leonardi wrote about the postcards on her neighborhood Internet mailing list. A University Park resident contacted The Washington Post, and a reporter and a researcher quickly tracked down Beach’s son, Jeffrey.

Beach doesn’t know what happened to the envelope she mailed the cards in.

“I was really surprised. I thought, my goodness, isn’t that funny,” Beach said last week when her son told her that the postcards were delivered to her old home. “I called my sister and told her what happened, and she laughed and laughed.”

For Beach, the postcards brought back memories of when she and her husband, who died six years ago, were newlyweds.

She said she remembered living in an upstairs apartment in Prince George’s County, the first place the couple settled after Calvin Beach returned from serving overseas.

“I’m just surprised I still had them,” Wanda Beach said of the 68-year-old cards.

Leonardi said she was glad the mystery had been solved.

Jokingly, she said she that almost began to worry about going to her mailbox after the second card arrived. She wondered if there could be more.

If there were, she laughed, she was going to start questioning whether she was “being stalked by a ghost.”

Researcher Jennifer Jenkins contributed to this article.