What’s the difference between cc and To fields in e-mail


In most email clients you can send an e-mail to multiple recipients in the To: field by separating addresses by a semicolon.

You can also use CC to send a copy to other people. Is there any difference between the two? Do mail programs behave differently depending on whether you CC or multi-To?

Best Answer

It is described in RFC 2822, and more precisely section 3.6.3 of that RFC.

Here's the actual fragment that describes usage of "To" and "Cc":

The destination fields specify the recipients of the message. Each destination field may have one or more addresses, and each of the addresses indicate the intended recipients of the message. The only difference between the three fields is how each is used.

The "To:" field contains the address(es) of the primary recipient(s) of the message.

The "Cc:" field (where the "Cc" means "Carbon Copy" in the sense of making a copy on a typewriter using carbon paper) contains the addresses of others who are to receive the message, though the content of the message may not be directed at them.

The difference between "To" and "Cc" is in semantics, and determines how recipients should treat the message (as directed to them or "copied" only for their information).

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