Forget all of the above.
A course's voting page will have a button "I dropped this course". This will add another section at the top with questions about why the participant dropped the course (Likert about most frequent reasons and free text). "No answer" will be selected for all other questions of the course's questionnaire.
On the student's semester page next to the "evaluate" button of each course a button "I dropped this course" will be added - this will have the same behavior as opening the questionnaire normally and then clicking the "dropped course" button.

The results of the special questionnaire will be shown only to staff, reviewers and responsible contributors. The participants will see an explanatory text on top of the questionnaire during the vote stating this information as well as an invitation that all other questions below can still be answered.

This keeps all information on the platform (no email to the admins - direct feedback for responsibles) and allows participants to still answer some or all of the "regular" questions.

For anyone tackling this: It may be helpful to browse through the old attempt to implement this in #1153. Some parts of this implementation are probably still usable. Make sure to have the design considerations from #1153 (review) in mind.

I would like to try tackling this

@janno42

Forget all of the above. A course's voting page will have a button "I dropped this course".

Should this button be shown for all courses? Or only for specific course types? Or should this be a selectable option at the time of the course creation?

(@janno42) As discussed, we want:

• A check-box "Allow drop-out?" when creating new evaluations
• A setting "DROPOUT_QUESTIONNAIRE_ID" to set which questionnaire should be shown when using the drop-out function.
• The "I dropped this course" button should be shown only on the student index and only for evaluations that "allow drop-out"