Speaking to IT Security Guru, Brian Spector, CEO of CertiVox, said that the PrivateSky product was shut down in January/ February of this year, after it had previously introduced a web-based version in beta and for Outlook and had "tens of thousands of heavily active users".
Spector said: "Towards the end of 2012, we heard from the National Technical Assistance Centre (NTAC) which is a division of GCHQ and a liaison to the Home Office, who served us with a RIPA warrant and they wanted the keys to decrypt the customer data. We did it before Lavabit and Silent Circle and it was before Snowden happened.
"So they had persons of interest that they wanted to track, and when they come with a RIPA warrant that is signed by the Home Secretary and you have to comply with a RIPA warrant or you go to jail.
Source: International Business Times. Read full article. (link)