I have never had any issues with Optimum Online's (part of Cablevision) webmail platform until yesterday. The website can be accessed and everything except sending mail worked properly when connected to Tejat (184.75.221.195). I spoke with customer support and they confirmed the cause is that they are blocking that IP address because of a third party spam filter they use. They provided the following link to show that particular IP was blacklisted by at least two third parties. http://mxtoolbox.com/SuperTool.aspx?action=blacklist%3a184.75.221.195&run=toolpage I disconnected and connected to Gorgonea and was able to send email so it might only be limited to a few AirVPN servers, possibly only the one. I imagine this would mean that there is additional impact for other users of any other email service that uses those same third party spam filters.