Hi Sarah,
First question, which kind of assignment are you using and which Moodle version?
In Moodle 1.9 through 2.2 advanced uploading of assignments, any text entered into the feedback box will be messaged to the student, if the send feedback notification box is checked. If the student is not logged into the classroom, the feedback is emailed to the student. Again, if the send notifications box is checked.
Attachments are NOT emailed. Students need to login to download and view attachments.
We don't use the Enable Send for marking feature, but it looks to me like the limit on submit/reset to draft is set by the number of files a student can upload.
I think, Sarah, you're missing an important way to view Assignment activities as a student, especially if you are in Moodle 2+. The "switch to student view" really misrepresents what students actually see.
You need to create a fake student. Put the student in the course and, if applicable, group. Logout as a teacher or other role. Login as the fake student. You will see that how students see their teacher feedback is rather straightforward. Go both to the assignment activity and to the gradebook.
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