SiteLock probes your site to determine if any of the fields and forms on it may be vulnerable to hackers attempting to exploit these forms to gain access to your data. (SiteLock does use similar techniques to test your pages, but you do not need to worry; their process is safe). SiteLock’s investigation will result in attempts to submit forms on your website with encoded data.
To stop receiving these emails or entries, validate the fields within your form to ensure that data is being submitted in the correct formats, before triggering emails or database inputs. Since SiteLock inserts data that would not likely be valid for any fields on your site, these validation measures should stop you from getting these empty emails or entries. It’s also good coding and security practice to make sure your site’s visitors are providing the correct data in the expected formats.