6.6 Encrypting Non-Email Data

Zoom Mail Service users can also have sensitive information in their user accounts that don’t directly correspond to any email they sent or received. These include custom labels, folder names, and email signatures. The Zoom Mail Client encrypts all of this information for the user’s own most recent email PUK, but the server still learns metadata such as the fact that two emails are in the same folder. Email drafts are encrypted and decrypted in essentially the same way as they would be when they are sent/received, except that the sender does not create recipient box ciphertexts for recipients (other than themselves) until the email is actually sent.