I have seen services advertising that they can message the followers of pages and accounts on Facebook. I have gone over lots of different Facebook API's and several interesting threads on here but cant find a definitive answer.
Is is possible to directly message via a bot users who like a page providing obviously we have a valid admin token for that page?
Is is possible to directly message via a bot users who like a page
No, that is not possible.
All communication via the Messenger platform API (basis for “bots” in Facebook terminology) requires that the user initiates it.
And it would probably be considered spam by most people - just because I liked your page, does not mean I want to be contacted by you in any way beyond that. Posting to your page is the designated way of communicating with the people that follow your page.
