Blizzard have posted their new policy for advertising services as of patch 9.2.7, as any boosting, carrying or similar services being advertised outside of the new Trade (Services) channel will be considered spam and “the proper actions will be taken”.
Services Advertising Policy (Source)
This week the 9.2.7 update introduces the new chat channel: Trade (Services). The Trade (Services) chat channel is used for searching and advertising services like raiding, dungeons, or PvP activities, keeping the original Trade chat channel available for traditional buying and selling of items and profession services.
With the separation of trade services into its own chat channel, a new policy will take place. Any boosting, carrying, or other similar services offered for gold that’s advertised outside of the Trade (Services) chat channel will be considered spam and the proper actions will be taken, so be sure to switch your service advertisements to the new chat channel when it becomes available after this week’s regional maintenance.