At this time we do not have the functionality in place to allow you to block Issue submissions from the SDK at the Dashboard level. The workaround is to set the ‘enableContactUs’ flag to ‘NEVER’ for select profile IDs in the SDK, and also maintain a blacklist in the server so that the emails can be filtered against this list. Please work with your developer to add this functionality into your application.
To learn how to block an email address, see How do I block an email address?