Since 1969, Jersey and Guernsey have operated postal administrations independently of the UK's Royal Mail, with their own postage stamps, which can be used for postage only in their respective Bailiwicks. UK stamps are no longer valid, but mail to the islands, and to the Isle of Man, is charged at UK inland rates. It was not until the early 1990s that the islands joined the UK's postcode system, Jersey postcodes using the initials JE and Guernsey GY.

Can we conclude that is jersey part of the uk royal mail?
no