Circulating social media, the cards feature the official Kensington Palace crest and feature a short note that reads: 'Prince Harry and Ms. Meghan Markle were incredibly touched that you took the trouble to write as you did in connection to their forthcoming Wedding.
A senior royal source said: "They would have loved Frogmore for the party, particularly Meghan, who has called it "dreamy", but they have been told St George's Hall is far more practical".
Prince Harry and Meghan Markle head inside the Reprezent studio.
The US former actor was cheered by hundreds who turned out in the January chill to see the couple at Reprezent 107.3FM in Brixton, which trains hundreds of young people every year in media and employment skills. The account even shared photos and videos of the couple's royal event today.More news: Margaret Atwood leaves her mark on Golden Globes
Shortly after Harry and Markle's engagement, Kensington Palace also announced that Markle would no longer carry on her charitable work with World Vision and as a United Nations advocate and would join of the Royal Foundation of the Duke and Duchess of Cambridge and Harry, as the main vehicle for their philanthropic activities.
The Palace has already been including Meghan in its public posts, ever since she and Harry announced their engagement.
On an impromptu walkabout later, she was showered with flowers and cards as she shook hands with the crowd, expertly steered by Harry.
The couple is planning to Wednesday on May 19, 2018, at St. George's Chapel at Windsor Castle.