How to send Kate Middleton a card as she battles cancer — and possibly get a reply

Grab a pen and a Hallmark card, because it’s time to get on down to the post office.

Kate Middleton supporters can now send her messages of love and support as she battles cancer.

An X user recently shared that the royal family sent her back a sweet reply after she mailed a letter of well wishes for the Princess of Wales, 42.

Fans now have the opportunity to send cards to Middleton as she recovers. Geoff Robinson/Shutterstock

Middleton went through a planned abdominal surgery in January before being diagnosed with cancer.

“Back in January when we were informed our beautiful Princess of Wales had undergone surgery, I sent her a card with our (my family and I) sincerest best wishes for healing and of course an abundance of love,” the fan penned on social media on April 6.

She then noted that Kensington Palace replied to her, mailing her a letter with their stamped insignia.

The post went on: “Today I received this beautiful acknowledgement and I can honestly say I shall treasure this my entire life.”

She joked that her husband thought at first he “was going to have to get his suit out for a garden party (silly him).”

“But he is just as blown away as I am to received this beautiful, and much treasured card. Continued prayers and healing to our beautiful Princess of Wales,” she gushed.

The office of the Prince and Princess of Wales replied: “Thank you for your kind well wishes to Her Royal Highness. Your thoughtful gesture is very much appreciated.”

Others can address their letters to “Kensington Palace, London W8 4PU.”

In March, the Duchess of Cambridge announced that she was stricken with cancer. BBC Studios

King Charles, who is stricken with cancer, will also joyfully accept get-well cards during this difficult time.

Those interested can send to “Buckingham Palace, London SW1A 1AA, United Kingdom” with the receiver scribed as “His Majesty The King.”

“The King is shown almost all of his correspondence on a daily basis by one of his Private Secretaries, and he takes a keen interest in the letters he receives,” the royal family’s official website reads.

In February, the Firm shared a clip of Charles happily reading some of his get-well cards in his home office at Buckingham Palace that were sent to him following news of his diagnosis.

The king read some get-well cards back in February. POOL/AFP via Getty Images

According to the etiquette guide Debrett’s, there are proper ways to write to members of the royal family.

“Unless you are personally known to the Sovereign, any letter to The King or Queen should be addressed to ‘The Private Secretary to His Majesty The King,’ ” the guide said.

When addressing Charles, 75, or Queen Camilla, 76, the letters should start with ” ‘Sir,’ ‘Madam’ or ‘May it please Your Majesty.’ “

After securing a postage stamp and envelope, just sit back and wait for a possible reply from the throne.