To, Cc, Bcc and Reply all: when to use each

The lines

• To is for the people you need to act or answer.
• Cc is for people who should know about it but do not need to reply. Everyone can see who was copied.
• Bcc hides the recipients from each other. Each person sees only the sender and the To line.

When to use Bcc

Use Bcc when you email a group of people outside your company who do not know each other: clients, event guests, a mailing. Putting everyone in To or Cc shares every address with every recipient, and some of those addresses may be personal. It also lets a reply-all go to everyone.

For regular mailings to many people, a proper mailing tool or a distribution list is better than a long Bcc line.

When to use Reply all

Reply all when everyone on the thread needs your answer. If only the sender does, reply only to them. A good test: would every person on the list be glad to receive this?

Be careful replying all to a message where you were Bcc’d. Your reply reveals that you received it.

One more habit

Check the To line before you send, especially when Outlook fills in a name for you. The wrong “Chris” is one of the most common ways information ends up in the wrong place.