Webmail struggles to offer security reassurances when utilising public key encryption. For example if Google allowed you to upload your private key and email would be transparently decrypted, that would be a great user experience, but now you have no way of knowing if the NSA&#x2F;GCHQ&#x2F;etc forced Google to give them your private key.<p>If you didn&#x27;t upload your private key to Google now you need your browser to decrypt your message in-line but preventing the website with the encrypted version from stealing the resulting decrypted version from the secure container. So that requires every browser to add these secure containers, for content to be marked for decryption, and for key storage.<p>If you aren&#x27;t worried about usability then you could just write a Word document, encrypt it and attach it to an unencrypted email. No browser support, or website support needed.