How true that is I do not know but it’s quite a claim. and it is alleged that even the NSA cannot break their encryption. ProtonMail for example is based outside the U.S. Each offers SSL encryption, little or no logging and are about as safe as it gets right now.
Secure email services such as ProtonMail, Tutanota, Kolab Now or Countermail offer free or mostly free encrypted email. For truly secure email, you have two main options, use a secure service or host your own. They make try to keep your email safe from the outside but they aren’t shy of helping themselves to your data. While they like to tell you otherwise, Gmail and are not secure email services. Nobody can track you, your data is encrypted and it makes life exceptionally difficult for anyone watching. Whatever you do online, you should always use a VPN. From there it goes out into the internet. Virtual Private Networks create a secure encrypted tunnel between your device and the VPN gateway. Rather than sending your network traffic, including emails in the open, use a VPN. You can use a VPN on desktop, laptop, tablet and mobile so there really is no excuse. This is true for every electronic device you might use.
Regular updates are released to plug these weaknesses so you should always keep your programs up to date.
Many viruses, Trojans and malware target weaknesses or vulnerabilities within a browser or OS. Keep your browser and operating system up to date.