The Metropolitan Police said that officers tested a substance in a package received at St James's Palace, which the London Evening Standard said was a white powder.
It seems that the specialists were rushed in to examine the letter and the powder that was inside the envelope and eventually it was deemed harmless. The former Kensington Palace press officer will be taking care of Meghan's diary and all of the correspondence she receives.
The power was found to be harmless.
The troubling incident came a day before police revealed a similar package containing white powder had been sent to the Houses of Parliament.
"The substance was tested and confirmed as non-suspicious", police later said in a statement.
The Evening Standard said the package was sent there for sorting before delivery.
Detectives have now launched an investigation to track down the sender of the letters but have made no arrests.
Miss Markle will become an official member of the Royal Family following her wedding but she has already been given round the clock protection.
Last October a terror suspect allegedly encouraged extremists to attack Prince George at school.