(difficulty: easy, requires teacher access to a course in a Moodle instance able to successfully send email notifications) Log in as a teacher and go to a course with a forum activity with some end users already subscribed to it Reply to a discussion by using a text+image post: add an image in the post by clicking on the related button in the Editor Browse the repositories and upload an image file that will be selected and the press Save image Post the message checking the Mail now checkbox too Check a subscribed user mailbox: the email will appear apparently without the image BUT if you access the source of the email you'll find a link to that image, e.g. http://www.example.com/moodle/pluginfile.php/MM/mod_forum/post/NNN/filename.ext (NOT @@PLUGINFILE@@/filename.ext ): if you'll put that link in a browser tab within the same authenticated Moodle session you'll see the "missing" image