I help artists and entrepreneurs become more successful by teaching them how to produce or promote themselves on the web.
As others have said, if you have their email list you can create an audience through Facebook so that you can use re-targeting ads to get them to register for your newsletter list (assuming there's a specific newsletter list).
You can also set up a retargeting pixel to target everybody on Facebook who's visited your site/URL to target "warmish" through Facebook ads.