Jase Hyndman, seven, and his ten-year-old sister lost their dad four years ago in May 2014.
Ever since then, the brother and sister have done something to mark the occasion in his memory.Â
This year, Jase posted a birthday card to his dad and asked the local postman to lend a helping hand.Â
He wrote: ''Mr postman, can you take this to heaven for my dad's birthday. Thanks.''
Much to his surprise, Jase from West Lothian, received a reassuringÂ letter assuring him that his message to his father James had made it through the "difficult" journey.
In response to Jase's envelope requesting to be sent to "heaven", Royal Mail's Sean Milligan said: "I just wanted to take this opportunity to contact you about how we succeeded in the delivery of yourÂ letter, to your dad in heaven.
"This was a difficult challenge avoiding stars and other galactic objects on route to heaven," the note added.
It concluded: "I will continue to do all I can to ensure delivery to heaven safely."
Posting the heartwarmingÂ letterÂ to Facebook, mother Teri Copland said: "I actually cannot state how emotional he is knowing his dad got his card... Royal Mail you've just restored my faith in humanity."
The Facebook post with Royal Mail's response to Jase was shared more than 200,000 times.
Ms Copland said: "He was overwhelmed and kept saying 'my dad really got myÂ letter mum'... I've always told Neive and Jase even if you can't get anyone a present it's always nice to make sure you send a card at Christmas and birthdays.
"I want people to realise that a small gesture of kindness can have such a fantastic impact on someone's life... Royal Mail actually took part and that gives me so much comfort."