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鈥檚 home.

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

鈥淚t helps, because there are lots of times during the day鈥� I find myself talking to her,鈥� he told CTV Atlantic, motioning to a framed photo of Ellen.

He鈥檚 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.

鈥淧lease mail a note, card, picture, map or story,鈥� , providing his Sydney address. 鈥淒AD LOVES COLORFUL DUCT TAPE, COZY SOCKS, CHOCOLATE and CRYPTOQUOTE PUZZLES,鈥� she added Wednesday after an overwhelming response. 鈥淛ust throwing that out there.鈥�

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鈥檚 Eskasoni First Nation and offered their best wishes in the Mi鈥橩maq indigenous language. 鈥淚 hope to visit you one day when I go to Eskasoni,鈥� . 鈥淚 hope to also meet your wonderful daughter who is connecting the world with you.鈥�

A teacher in Ontario posted a photo of a pile of written for Dunn by her students. 鈥淵OU GO GERARD!!! 92 and going strong,鈥� 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.

鈥淗e finds ways to make the world a better place and now he鈥檚 getting what he deserves back,鈥� his daughter said.

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

鈥淚鈥檓 so amazed at it that I鈥檓 speechless,鈥� said Dunn. 鈥淔or them to do that I think is just wonderful. There鈥檚 no way I can thank them.鈥�

With a report from CTV Atlantic鈥檚 Ryan MacDonald