NEW YORK (CBSNewYork) – When you’re mailed letters belonging to someone else, you say “return to sender” or you can turn them into acts of kindness.

That’s what happened when letters to Santa started turning up by the hundreds in a random Manhattan mailbox, CBS2’s Dave Carlin reports.

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“I like the ones they have the drawings on them because they’re really cute,” Jim Glaub, the founder of Miracle on 22nd Street said.

Jim Glaub reads one of the many letters for Santa sent to his apartment. (Credit: CBS2)

Glaub has no qualms opening thousands of letters not addressed to him and he’s certain Santa Claus won’t mind either.

“I’ve been a good girl… but my Mom does not have much money for my Christmas presents,” Glaub read from a letter.

Glaub, who lives far away from the North Pole, intercepts kids’ Christmas wish lists because they mysteriously land in this ordinary mailbox on West 22nd Street – for an apartment he shared with his now ex-husband.

A decade ago letters arrived by the dozens, then suddenly jumped to the hundreds. At first, he was irritated.

“We did go to the post office and they were like ‘we can’t help you.’”

Then, the more he read, the more he said “ok, we just need to help do a little bit of what we can.”

He picked a single letter and helped a family.

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Loved ones, friends, and colleagues did the same.

“I love all the creativity that they put into the letters,” Glaub’s co-worker said.

The effort grew from there, first on Facebook and now it has 500 requests for this Christmas – with a dedicated “Miracle on 22nd Street” webpage, partnerships with charities, and hundreds of kind-hearted helpers.

“Once you do it you’re hooked,” one of the “elves,” Amanda Lehner said.

There are so many letters, but also many unanswered questions as the letters came to different tenants long before Glaub moved in.

It is an unsolved mystery, but there are two theories, one being that there was someone who lived in that apartment in Chelsea before them that ran some sort of charity. The other theory dates back to the 1800s.

“The area was part of Chelsea Square back in the 1800s and that area was owned by a guy named Clement Clarke Moore who wrote ‘Twas the Night Before Christmas’ and he was getting letters to Santa,” Glaub explained.

Glaub says he no longer asks why.

“It’s the best feeling in the world to feel that you can help a little bit is the greatest,” the Secret Santa said.

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The nationwide push for “Miracle on 22nd Street” comes as the tale gets told in an upcoming Universal Studios movie, written by Tina Fey.