We have just learnt that protonmail.ch now for a limited time allows everyone (friends of current users) to register and use their secured email servers instantly.  And they give 1G space instread of 0.5 G to those who register before June 17, 2015.   In the past, use of the servers was only for those who were invited due to the limited space.To register, go to https://protonmail.ch/privacyforallThe biggest difference between protonmail.ch and other email providers like yahoo.com, google.com and hotmail.com is that data in the email servers provided by protonmail.ch is secured, which means no one including server administrators and governments and hackers could have access to the data.After June 17th, people can still register and use protonmail.ch, but they will have only 500M or 0.5G data for free.