An 11-year-old boy who lives with autism had his birthday wish come true, thanks to his older sister.

It all began when Kristian Hayes’ sister Kaitlyn posted a picture on Facebook, asking for help with her brother's birthday.

Kristian has always been fascinated with letters and stamps.

“Every day he asks for mail to my grandfather, ‘did I get mail? Did I get mail?’ and the answer is no,” says Kaitlyn, “I decided it'd be nice for him to get some mail.

He gets on my nerves sometimes, but I love him.”

Kaitlyn’s Facebook request included their family address and a plea for strangers to send mail to help make her brother’s birthday special.

It didn't take long for postal workers in Stellarton, N.S. to notice the increased traffic at one mailbox in particular.

“We understood first when it was coming through the mail,” says Ian Dewar, with Canada Post. “There was so much and then we heard through some of the people that follow Facebook and it just seemed to catch on.”

Kaitlyn had hoped that 50 people would send her brother mail and that goal was well surpassed.

“We've received well over 3,500 cards,” says Kristian’s mother Heidi Hayes. “They came from everywhere. They've come from the United Kingdom, Australia, France, Netherlands, everywhere you can imagine, we've had mail from.”

The post office hosted a special party for Kristian’s birthday Wednesday, and surprised him with another 600 letters.

There was a cake on hand to celebrate the special boy’s birthday, and also the kind act by his loving sister.

“She gave me presents,” says Kristian. “I was scared and she was there for me and I love her.”

“She's only 15 months older than Kristian, she's 12, and honest to god, she is so mature for her age and she carries herself so very, very well and she just loves her brother so very, very much,” says Heidi.

Kristian was blown away by the day’s events and all the mail he has received, declaring it his best birthday ever.

With files from CTV Atlantic's Dan MacIntosh