def send_preview(recipients, personalize="fallback")
      options = { :body => {
        :PreviewRecipients => recipients.kind_of?(String) ?
          [ recipients ] : recipients,
        :Personalize => personalize }.to_json }
      post "sendpreview", options
    end
def send_preview(recipients, personalize="fallback")
      options = { :body => {
        :PreviewRecipients => recipients.kind_of?(String) ?
          [ recipients ] : recipients,
        :Personalize => personalize }.to_json }
      post "sendpreview", options
    end
Sends a preview of this campaign.