ChiaraMail is described as 'Secures e-mail content in transit without encryption, stops spoofing and phishing, enables users to change or delete their e-mail content after it has been sent, lets users send large attachments directly to recipients (no need for Dropbox, etc.)'. There are more than 10 alternatives to ChiaraMail for a variety of platforms, including Online / Web-based, Android, iPhone, iPad and Linux. The best alternative is ProtonMail, which is both free and Open Source. Other great apps like ChiaraMail are Tutanota (Freemium, Open Source), mailbox.org (Paid), Yandex.Mail (Free) and Vivaldi Mail (Free).
mailbox.org offers a secure e-mail account for home and business use. The domain name, email@example.com, is easy to remember and can be understood anywhere in the world. They have been operating e-mail accounts for more than 20 years and are a highly reliable service provider.