TL;DR: Use BCC when emailing a large group who do not need to reply to one another. It protects their email addresses and prevents accidental Reply All messages from reaching everyone.
When emailing a large group of people who do not need to see one another’s responses, consider adding their addresses to the BCC field rather than to the To or CC field.
BCC stands for Blind Carbon Copy. Everyone receives the message, but recipients cannot see who else it was sent to. If someone selects Reply All, their reply will not be sent to everyone included in the BCC list.
BCC is helpful when:
Sending an announcement or update to a large group
Recipients do not need to discuss the message together
You want to avoid unnecessary Reply All responses
The recipients’ email addresses should not be shared with one another
Emailing people outside the organisation who may not already know each other
A simple approach is to place your own email address in the To field and add all recipients to BCC.
Use To or CC instead when recipients need to know who else is involved or when a group discussion is expected. BCC is excellent for distributing information but less suitable for collaborative conversations.