Aside from his own piano playing, the metallic clink of the front door mail slot has become one of the sweetest sounds in 91-year-old Gerard Dunn’s home.

After his wife Ellen died in March, the Nova Scotia man has caught himself waiting for the sound that signals he’s got mail. It’s become the highlight of many of his days.

“It helps, because there are lots of times during the day… I find myself talking to her,” he told CTV Atlantic, motioning to a framed photo of Ellen.

He’s likely to hear the sound a lot more over the next few weeks since his daughter Miriam took to Twitter on Monday to ask users to send him birthday cards. Dunn, who worked for the post office for 55 years, will turn 92 next month. The tweet has been shared more than 20,000 times and liked more than 42,000 times since Monday.

“Please mail a note, card, picture, map or story,” she wrote, providing his Sydney address. “DAD LOVES COLORFUL DUCT TAPE, COZY SOCKS, CHOCOLATE and CRYPTOQUOTE PUZZLES,” she added Wednesday after an overwhelming response. “Just throwing that out there.”

She expected to get just 20 to 30 cards from the tweet, but scores of users quickly began sharing photos of cards and sealed envelopes. One letter from a doctoral student in Montreal said they were originally from the province’s Eskasoni First Nation and offered their best wishes in the Mi’Kmaq indigenous language. “I hope to visit you one day when I go to Eskasoni,” the letter posted on Twitter read. “I hope to also meet your wonderful daughter who is connecting the world with you.”

A teacher in Ontario posted a photo of a pile of colourful letters written for Dunn by her students. “YOU GO GERARD!!! 92 and going strong,” read one.

The first of many expected letters arrived Wednesday from a man in the northern Nova Scotia village Tatamagouche. Others are apparently on their way from South Africa, the U.K., Australia and Spain.

“He finds ways to make the world a better place and now he’s getting what he deserves back,” his daughter said.

The response to the original tweet was so strong, Miriam posted her own address in a follow-up tweet for letters to be sent.

“I’m so amazed at it that I’m speechless,” said Dunn. “For them to do that I think is just wonderful. There’s no way I can thank them.”

With a report from CTV Atlantic’s Ryan MacDonald