1/ So for you reporter/journalist people (you people), I thought I'd write up a brief styleguide on what "cc:" means in email headers, should you use "courtesy copy" or "carbon copy"?
2/ The question arrises from the recent "China hacked Hillary's server", where the anonymous expert is quoted discussing "courtesy copy" headers in emails.
3/ The correct answer here is "cc". That's probably what the original expert said, "CC header". By attempting to help the reader understand, the journalist probably expanded it to "courtesy copy" -- what they believe is the acronym "CC" stands for.
4/ But the "technically correct" meaning is not "courtesy copy", but "carbon copy", as specified in the earliest email specifications from the 1970s, and in official Internet standards:
ietf.org/rfc/rfc2822.txt
ietf.org/rfc/rfc2822.txt
5/ This is a problem, but it calls into question whether the anonymous sources actually had sufficient expertise to understand the evidence. Maybe China did hack Hillary's server, or many inexperienced non-experts misunderstood the evidence.
6/ Your highest journalistic responsibility to not lie, to tell the truth. When you deliberately change technical details, such as changing "cc header" to "courtesy copy header", you are no longer telling the truth. You've changed the facts of the story from one thing to another.
7/ It doesn't mean you can't do your best to explain things, it means you can't change it. In other words, you can explain the "cc" means "courtesy copy", you just can't remove "cc" from the story.
8/ A lot of you want to write "statements of record", where it's your story that becomes the basis for future reporting on the topic, the one that everyone refers back to. You can't do this when you've garbled the facts such that the reason we refer to it is to question it.
9/ Now as for which term you should use, "carbon copy" or "courtesy copy", I'm not going to insist that you must use the "technically correct" version. Language changes, and I'm not going to insist on techies owning the word.
10/ As far as I can tell, the legal community understands this as "courtesy copy", reflecting something they often do even before email, giving out copies as a courtesy when doing various legal thingies. So if that's your audience, that's not incorrect.
11/ However, in my review of various email programs/services, as well as searching on the Internet, it seems like the correct definition isn't even "carbon copy" either: it's "cc". An example is how Mirriam-Webster defines "cc": 
12/ So my ruling is this: "cc" means "cc". I know you want to expand acronyms, but no, don't do that here. It doesn't actually explain the term any better. It does distort the facts, which you should never do.
