I personally don't like receiving a new email thread every day and many students also dislike this because it fills up their inbox.

I think a potential mitigation would be to use threads, i.e. each new email is In-Reply-To the previous email. This would be been trivial if I use normal email systems, but Microsoft Graph is not normal. But there's definitely a way to do so; sendmail.py isn't really complete either so this sounds like something I should implement soon.