If you sent someone an important email and they did not respond (yet your email did not ask for a response), would you give them a hand written note, in addition?

I asked a question on here a few weeks ago about scheduling my daughter’s birthday party. In the question, I said that there are two other kids in her class that might have parties at the same time. One of the answers suggested I contact the other two parents to tell them our party date, so there are no misunderstandings.

I decided to use email since it’s neat and efficient. I sent both sets of parents a brief email letting them know the date and explaining my reasoning for the email – so that there are no conflicts. I did not ask for a response. One set of parents responded. The other did not. Should I put a hand written note in the child’s box at school, to the parents? I got their email address from the teacher, but you know with email there’s no guarantee that it’s been received, for various reasons.