digital stranger
A person that you temporarily treat as a close personal friend that which you have met via digital means, i.e. online, IM, mobile, etc, that you affiliate, support, recognize and/or communicate with in some form but yet, you have never physically met "live, or "in person"; face to face.
When I get a heart felt reply, sent to me via text message 2 or 3 months after I sent the original message; I reply to them as a if they are a digital stranger.