We are currently using Moodle 2.7.1 Build 20140714.
In a hidden Moodle course, messages posted to the News Forum are being sent to all users. This causes confusion because the users/students can't then see the message in context.
I had assumed that if a course (or forum) was hidden, messages would not be sent to participants.
A previous tracker ticket (MDL-5697) was posted a few years ago regarding a hidden forum sending messages.
In our case, the entire course is hidden and lecturers who are new to Moodle, have been practising editing Moodle and therefore using the News Forum in a test capacity. They, and we, assumed messages would not be sent out.
I'm not sure if this is a bug or a strange feature but perhaps someone could let me know or perhaps know a way of fixing it.
I have added it to tracker as well - https://tracker.moodle.org/browse/MDL-49651