E-mail alerts for Submission comments would be a great thing. I'm surprised to see no settings for Submission comments at Site administration / > Plugins / > Activity modules / > Assignment / > Submission plugins / > Manage assignment submission plugins ... All I can do is disable the plugin globally, sad.
Or else the teacher - as before - should be able to turn this feature off per assignment, as used to be the case - cf. http://it.umn.edu/moodle-24-26-including-student-comments ..