lib/createsend/campaign.rb
def email_client_usage
      response = get "emailclientusage", {}
      response.map{|item| Hashie::Mash.new(item)}
    end
def email_client_usage
      response = get "emailclientusage", {}
      response.map{|item| Hashie::Mash.new(item)}
    end
Gets the email clients that subscribers used to open the campaign