Why isn't it possible to share my article in the mailing?

The condition for activating social media is that a link with tracking is included in your content block. A trackable link is a link for which the clicks on the link are measured. Make sure you add a link in your content block. Add a link to the button by clicking on Insert/edit link.

Insert_edit_link.png

Next, select External link with tracking. Now you can add Social media using the drop-down menu in the block bar.