Sending same text to many people, nobody sees other recipients
You should use the Bcc (blind carbon copy) function found in all mail software, web- or app-based.

“A blind carbon copy (Bcc) of any correspondence is sent when you wish to conceal the fact that there are other recipients of the message. You might do this to discretely let somebody else in on a conversation, to send email to a list without sharing everybody's email or involvement with everybody else, or any other situation where you might desire a bit of privacy.”

From:

https://m.wikihow.com/Use-BCC-in-an-Email