UPDATE, March 13, 2014: Twitter has implemented STARTTLS for emails sent from its service to users—an especially important step, given that the contents of Direct Messages may be included in these updates. We‘ve updated the chart to recognize their work in that category, bringing the company to a full five checkmarks.

Tumblr has released optional SSL as a setting for logged in users viewing their dashboards, and plan to roll it out as a default in the next several months. HSTS support is still planned in 2014.