CakePHP datasource for connecting to the mailchimp API ( http://apidocs.mailchimp.com/api/ ) as well as the Mandrill API ( https://mandrillapp.com/api/docs/ )
Returning false in MailchimpAppModel::call() is problematic: the campaignCreate function returns an array with [..., 'status' => 'save', ...] when successful for example. So it succeeds, but because it has a status key, it still returns false although you then need the campaign id to send it. Maybe it should return $this->response anyway all the time as a last resort? I don't know enough how other functions normally react to decide on the best course of action.
In the MandrillTransport class its impossible to send a template that is stored on Mandrill without having a local template available. Which defeats the purpose of the Mandrill templates. The code on line 127 and line 85 also prevent you from passing template_content vars to Mandrill.
I'm not sure if this is by design or I'm totally confused on the usage of it.