A popup menu will confirm how many people have been selected and allow you to draft a plain-text message to those recipients.
NOTE: We suggest mentioning your course in this message, as there is no other indication that the message is clearly from your course, only that is is sent in your name on behalf of Moodle.
Click the Send message to [number] people button when you’re ready.
Subsequently, you can follow up with each each individual via the Moodle Messages interface: the chat bubble icon in the top-right corner of the page.