Hi Daniel,
I forced sending of a Joomla! email, by creating a new user so it send the users registration.
Mandrill site dashboard shows 1 mail sent, 1 mail delivered, but the Joomla CMandrill dashboard is not showing any data.
Mandrill API key has been set.
I will work through this, as it could be a useful guide/checklist for any other users that may experience the same problem.