General help

Hi Rubén, I don't think you've missed anything per-say. This would be appropriate behavior by design as Moodle's platform is of a Social-Constructivism point of view (https://docs.moodle.org/311/en/Philosophy) where learners interacting with other learners is am important piece of the Moodle platform. Some of the hacks you were referring to may have worked with the old messaging system and may not work with the updated version back from I think Moodle 3.7 -- the biggest difference with the updated version compared to previous versions of Moodle is that there are settings to make sure students can only message other students within their own class instead of anyone on the site. Anything outside of that would most likely require custom development.