You can now share campaigns directly to Facebook Messenger on both desktop and mobile devices. When adding the share action you will see a checkbox for allowing sharing through Facebook Messenger.
For entrants, they will see the Facebook Messenger icon when they click the share action:
On desktop this will open Facebook and allow them to select friends to send the promotion to.
On mobile it will open the Facebook Messenger app if it is installed on the users phone. It will automatically populate the content of the URL it is sharing, and users just need to select friends to send it to.