Question

Why is it a mistake to put e-mail address of people who don't know each other in the "to:" field

Answer 1

They would probably think that you sent the email to the wrong person and then delete it.

Answer 2

Answer:

The person that you send it to will probably think its as scam or it was sent to the wrong person. But most importantly so that nobody's email address gets leaked. They did not consent to having their contact email shared with other people.

Explanation:

I wrote this myself, it is the correct answer. I took what the site said about email addresses and put it into my own words. I can guarantee you that you will get 100% with this answer!

Good luck on your class!