There’s a new workaround out that allows you to retarget anyone that clicks a link that you control. Meaning you can retarget anyone that clicks on any piece of content (especially curated content) that you provide.

Link retargeting is when you put your retargeting pixel code – be it Facebook, Google, Twitter, or otherwise – inside of a short link so that anyone that clicks on the link is added to your retargeting pixel.

This allows you to pixel people that are going from your social post to someone else's site (and there are a few similar applications). It’s perfectly legal and allowable, and honestly it actually serves additional value to your audience (assuming you continue to serve them well and not just relentlessly spam them).