It is prudent to clarify with your EMDR therapist that they have completed an accreditated EMDR training course and that they are legitimate mental health professionals, belonging to a professional body. It is also important that your EMDR therapist is being professionally supervised by another fully trained accreditated EMDR Consultant. This kind of consultation between professionals is a standard requirement in all areas of psychology, mental health and medicine.
EMDR is a powerful technique for which you should be carefully prepared by a therapist with whom you feel you have established a rapport and trust.