The joy of receiving a note from a member of the Royal Family, in response to a card or a letter, has long been keenly felt by well-wishers from across the globe.
But the Duke and Duchess of Sussex now face a scramble to make new arrangements for their correspondence after the Prince of Wales withdrew his financial support for the mail service provided by his team at Clarence House.
The couple's decision not to return to the royal fold as working members of the family means that all professional ties will be severed from the end of next month.
For practical reasons, that will include arrangements relating to their mail, the Sunday Telegraph understands, meaning that well-wishers might have to start posting their cards to the US instead.
The Correspondence Section at Clarence House, comprising around four members of staff, has traditionally handled the Sussexes' mail, as well as that of the Duke and Duchess of Cambridge, Prince Charles and the Duchess of Cornwall.
Thousands of letters and cards are received each month for each member of the family, all of which are carefully sifted and organised, with the majority generating polite replies on monogrammed paper, franked from Buckingham Palace.
While the Prince of Wales receives the most post, the volume of letters trickling in for the Sussexes is thought to have dwindled since they moved abroad.
But sackfuls are still received, with notable spikes around birthdays, Christmas or significant announcements.
The process is funded by the Prince privately, and while not a significant cost, still amounts to tens of thousands a year, comprising staff costs, overheads, stationary and stamps.
One issue understood to be behind the decision as well as that the royal office would also have no prior knowledge of events, campaigns or announcements made by the Sussexes that might prompt a sudden spike in mail.
A source close to the Sussexes said their new arrangements had yet to be determined, but pointed out that there was a Los Angeles address for the couple's Archewell Foundation on their website.
However, they will have to move quickly to deal with the expected deluge of congratulatory messages when the Duchess gives birth to their second child in early summer.
The couple's highly anticipated interview with Oprah Winfrey, to be broadcast in the US next Sunday evening, will also generate a significant response.
The 90-minute special, understood to have been recorded over two days at their Santa Barbara home earlier this month, will almost certainly ruffle feathers as they discuss their decision to quit as working royals.
An aide said audiences could expect the couple to expand on issues raised by the Duke in his interview with James Corden, broadcast last week, in which he discussed everything from his son's first word - crocodile - to the "toxic" British media that had been destroying his mental health.
Gayle King, a friend of Ms Winfrey and a CBS anchor, claimed the chat show queen had told her the interview was "'the best she has ever done."