PrinceHarry and Meghan Markle attend the Terrance Higgins Trust World AIDS Day charity fair at Nottingham Contemporary on December 1, 2017, in Nottingham, England.
The letter was intercepted before reaching the couple but a full security scare was sparked over fears it could contain anthrax. That powder was found to be harmless as well.
The couple will celebrate their wedding day with members of the public by taking a carriage ride through the town, although security is likely to be high after Britain suffered four deadly attacks blamed on terrorism past year.
It has now been revealed that Met cops rushed in when Kensington Palace received a letter for Meghan, 36, and Harry, 33. Markle, a successful actor who recently bowed out of her most prominent role in U.S. legal drama "Suits", is from a mixed-race background.
"The substance was tested and confirmed as non suspicious". Meghan has spoke out about her struggles growing up bi-racial in the past - her father, Tom, is Caucasian, while her mother, Doria, is African American.
The newlyweds will then embark on a carriage procession around Windsor before ending up at the town's famous castle. So far, no arrests have been made.
They are also believed to be examining whether there is a link between the two incidents.