Being on college faculty, I receive about 60-70 emails per day. Not all of them need response. Is there a way I can flag important emails, that I can return to them quickly at the end of the day?

Any help will be appreciated. Thank you in advance!

I don't think there is any way to do this on the iPad directly. Since I don't know what email system your school is using, you may need to get with your IT department and ask them about setting up "message rules" where you can specify what happens to emails when they arrive. If there are emails from your colleagues, staff or students, you can designate that these stay in your inbox and all others go to another folder of your choice (for example).

You are the only one who knows which emails from whom are a priority and your IT department should be able to set it up the way you want.