Cc header not working

From the plugin’s overview:

Note that if you’re sending additional headers in your emails, the only valid headers are From:, Reply-To:, and X-*:. Bcc: is also valid, but Mandrill will send the blind carbon copy to only the first address, and the remaining will be silently discarted.

I don’t see Cc listed there, and it says it ignores Bcc.

You might also try the array approach:

$headers[] = ‘Cc: John Q Codex <[email protected]>’;
$headers[] = ‘Cc: [email protected]’;