Forbidden Message When Submitting Contact Form

My client was able to duplicate a form submission error that has been an ongoing issue with her website. Multiple site visitors have reported this issue. She was able to get the “Forbidden. Your IP belongs to a high spam risk network. Anti-Spam by CleanTalk” and her email address is the same domain as the website! I’ve searched and searched as well as tried to make adjustments in settings to minimize this without luck. Please help me address and resolve this issue.

Many thanks