Interesting email I got today...

Good evening

I regret to inform you that I will request to drop from your course. Since the deadline is November 7, I will not be able to get you to sign the drop slip form. After speaking with the registration office, they adviced me to get an email from you as proof that I contacted you and notified you about my decision to drop your course.
Thank you for your understanding,

xxxxx xxxxx

Needless to say, I DON'T teach any classes.