Proton is one of the newer encrypted email services that have come along post-Snowden, with an emphasis on really keeping your emails private. They make a point of this by being based in Switzerland. However, they are still building their product out and as a result it has a very simple Web UI for its client and admin tool. The web client is responsive and can be used on mobile devices. They are also working on iOS and Android apps but weren't ready yet for this review.
Unlike some of the other services reviewed here, there is no mechanism for handling an entire domain: all email addresses have to be part of their protonmail.ch or protonmail.com domain. We include them in this review because they are so security-conscious and this is one of the first totally protected email services we've seen.
Because their servers are located in Switzerland, this is a big draw for people who don't want an American footprint. All of their investment capital to date has been raised through crowdfunding or other non-traditional sources.
Proton uses double password protection. The first is used to authenticate the user. After that, encrypted data is sent to the user. The second password is a decryption key used to decrypt data on your device. Proton never sees that latter key so they do not have access to the decrypted data. On top of all this encryption, they also employ SSL connections so your data is further encrypted across the Internet to and from their servers. There is no option to make use of any on-premises servers.
Unlike Hushmail, it doesn't support OpenPGP, but has developed its own algorithms.
You can also send messages to non-Proton users, where each message body and attachment will be encrypted with a one-time password. And you can send a password hint as an option. Another option is that you can set an encrypted message to expire after so much time has elapsed. Messages sent to other ProtonMail users by default are kept for a month at most.
While Proton would not protect against the Silk Road scenario, a user could register for this service anonymously so, like Hush, it would protect their identity.
Proton has a very simple UI for adding users too. Some of the other services allow CSV import.
While Proton is not really suitable for an enterprise deployment, it is a nice package of what the latest encryption products can deliver.
Mailboxes are fixed at 1GB per user, with attachments limited to less than 10MB. Each mailbox will cost $5 per month.
Of the products we tested, Tutanota is the least reliable and least feature-laden. It comes with a variety of clients, including web, iOS, Android, and Outlook plug-ins. Tutanota is a lot like CipherPost: it uses a variety of clients to set up encrypted mail connection across your existing email infrastructure. There are no changes to your servers and you can continue using Outlook for sending unencrypted communications.
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