Switch to data selection meaning? I'm setting up rules, trying to setup HTML emailing. I've it setup but not sure how to configure it. What does Switch to data selection mean?'
For an email action, there are 2 different input modes for the fields in Send HTML email action.


Direct input mode: You're supplying most of the data (e.g. the HTML body) with different token (e.g. [site:slogan]) inserted in it.
Data selector mode: You're using a widget (see image) that lets you drill into data that the Rules action has available. This is useful for finding contextual data (e.g. retrieving the current user's email when a node is updated).