cc 'carbon copy' - usually a 'fyi' courtesy email is useful if:
- if you are indirectly addressing someone
- you intend the recipient to be aware of those in the cc field
- to keep someone informed regarding a particular matter
- those cc'd don't have to directly reply or respond, usually
- all recipients may have need of all other recipients email addresses
- if you wish to keep a recipient 'confidential'
- if you wish to keep a recipient's email address 'confidential'
- if you do not wish to let the intended recipient be aware of a confidential recipient
- to protect all recipients agains spam
- if you do not wish to make the to & cc fields overly large ie. bulk email
reply all - 'I have never used reply all' could be useful if
- you would only use reply all if you required all the recipients of the original email to see your email reply.
- everyone receiving the original email is required to give feedback of some type