When sending an email to a group of people, really think long before CC’ing everyone and exposing their email addresses.
Sending an email to 30 people and CC’ing all 30 means you have shared all 30 email addresses with everyone else (and everyone else who might later on get forwarded the email). Furthermore, when people start replying with “reply all” now everyone is receiving even more useless “noise” when they get “thanks” or some other personal response.
The first question you should ask yourself is whether all of those people need (and want) to receive your email. If the answer is yes, then the next question is should they be CC’ed or BCC’ed. If you are inviting a small group over for something, it might make sense for everyone to see who else will be attending (or at least who is invited). However, if there isn’t a good reason to CC everyone, then DON’T!
If you receive an email with a lot of people CC’ed, really give some thought before replying to everyone. Do they all need to read what you are replying with?
Respect people’s inbox.
Have a great day!