def deliver
      SendWithUs::Api.new.send_email(
        @email_id,
        @to,
        data: @email_data,
        from: @from,
        cc: @cc,
        bcc: @bcc,
        esp_account: @esp_account,
        version_name: @version_name,
        locale: @locale,
        files: @files,
        headers: @headers,
        tags: @tags
      ) if @email_id.present?
    end
def deliver
      SendWithUs::Api.new.send_email(
        @email_id,
        @to,
        data: @email_data,
        from: @from,
        cc: @cc,
        bcc: @bcc,
        esp_account: @esp_account,
        version_name: @version_name,
        locale: @locale,
        files: @files,
        headers: @headers,
        tags: @tags
      ) if @email_id.present?
    end
Invoke <tt>SendWithUs::Api</tt> to deliver the message.
 The <tt>SendWithUs</tt> module is implemented in the +send_with_us+ gem.

 IMPORTANT NOTE: <tt>SendWithUs</tt> must be configured prior to calling this method.
 In particular, the +api_key+ must be set (following the guidelines in the
 +send_with_us+ documentation).