All API calls returning data about messages include a addresses property .
"addresses": { "from": { "email": stringemail address of sender, "name": stringname of sender }, "to": [ { "email": stringemail address of a recipient, "name": stringname of a recipient }, ... ], "cc": [ { "email": stringemail address of a cc'ed recipient, "name": stringname of a cc'ed recipient }, ... ] }