Lockbin is described as 'web application for sending private email messages and files. People use it to send things like credit card numbers or confidential information' and is an app in the Online Services category. There are more than 25 alternatives to Lockbin for a variety of platforms, including Online / Web-based, Windows, iPhone, Mac and Linux. The best alternative is ProtonMail, which is both free and Open Source. Other great apps like Lockbin are Tutanota (Freemium, Open Source), mailbox.org (Paid), Enigmail (Free, Open Source) and Yandex.Mail (Free).
mailbox.org offers a secure e-mail account for home and business use. The domain name, firstname.lastname@example.org, 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.
Mailvelope is a browser extension that allows to exchange encrypted emails following the OpenPGP encryption standard. Mailvelope integrates directly into the Webmail user interface, it's elements are unintrusive and easy to use in your normal workflow.
ShazzleMail is the first privacy-protective and surveillance-resistant secure email service. ShazzleMail doesn’t travel the web, but delivers mail directly from your smartphone. No server copies, no open access to NSA, and no big business data mining.