I remember one of my first training lessons when I got promoted to a manager at my first job. They taught me about taking complaints over the phone. The biggest thing I remember is "the power behind the phone." People would not say some of things they would say over the phone, if they were talking to you face to face. Some of those things, they wouldn't even normally think.
That has proved to be a very valuable lesson and one I believe has helped me in multiple facets of life. I believe that mentality can help those when communicating online as well.