CipherMail is a free Firefox extension designed for enhanced email security, allowing users to send and receive encrypted messages across various platforms like Gmail, Yahoo, and Outlook. Utilizing S/MIME technology, this tool ensures that email communications are protected with encryption based on certificates, which are generated automatically for each contact. The platform supports both plain text and HTML formats, ensuring that all message content and attachments remain secure during transmission.

The extension features a modern user interface that includes functionalities such as drag-and-drop file uploads, browser notifications, and multi-language support. It also integrates seamlessly with existing S/MIME clients, offers contact management with email address autocompletion, and employs a token-based security engine to safeguard against CSRF attacks. With compatibility for numerous email domains, CipherMail provides a comprehensive solution for secure email communication.