Drugs being ordered on the Dark Web are being sent to people hidden inside Christmas and greetings cards, according to Wiltshire Police.
A number of suspicious packages have been passed to the force after being intercepted at the Royal Mail sorting office in Swindon.
These packages, addressed to different addresses across the country were found to contain small quantities of herbal cannabis.
In a post on their Facebook page, the Swindon South Police said one card was addressed: "To Frankie, Happy Smoke Day."
A Royal Mail spokesperson said they are working with law enforcement agencies to stop the carriage and delivery of illegal substances.
"The Royal Mail understands the tremendous harm that illegal drugs cause in the community.
"We work closely on the ground with law enforcement agencies, including the police for domestic mail and with Border Force for international mail.
"We also encourage our postmen and women to report to their managers any suspicious items which we then promptly refer to the authorities."