Luckily, there’s an alternative to both of these: BCC, or “Blind Carbon Copy”. 

BCC works just like CC, except the recipients can’t see each other’s email addresses. This makes it more private.

When you get an email you’ve been BCC’d into, you can still view who sent it to you. However, you won’t be able to see anyone else who’s been sent the email via BCC.

Some serious leaks have taken place when a sender used CC instead of BCC.

While it’s easy to get them mixed up, if in doubt, always use BCC when writing an email to many people.