This is good article by Michael Fenichel, Ph.D.
Many counselors and psychotherapists, including those who meet with clients online, rely on close analysis of interpersonal dynamics between therapist and client, using the ‘here and now’ of that particular session. Surely this now happens, not only through the use of chat rooms replete with emoticons, but also through the familiar e-mail letter exchange, which (particularly with groups) may become part of a continuing subject ‘thread’ focused on specific issues. Many deeply meaningful and powerful relationships can be formed and/or maintained via the written letter. It may be ‘asynchronous’ communication, but it still is experienced as ‘here’.