I have often seen people writing a line like this in emails:
I have copied xyz on this email.
This reads funny to me. I always thought it should be "I have copied this email to xyz". That makes more sense to me.
Is the first usage correct? How did it come into being?
The Oxford English Dictionary definition 1c of the verb copy includes:
to provide (someone) with copies of correspondence, etc., on a particular subject for information. (Common in office use.)
The entry has this supporting citation from a novel published in 1983:
LaSalle pushed a file jacket across the table, and Harper flipped through the pages.‥ ‘You'll copy me on all this?’ said Harper.
So the answers to your question are that copy followed by a human direct object is established and recognised and that it has been around for almost 30 years, and possibly longer.
