Messages & Emails
Plaintext messages and drafts - Plaintext content of messages encrypted to the user’s public key(s) and the plaintext content of draft messages composed by the user.
Messages metadata - Subject and recipients of the encrypted messages, including key IDs of the message recipients, as well as encrypted message attachment filenames. Metadata can be disclosed to web applications for convenience and the purpose of routing an encrypted message to its intended recipients. Clients traditionally encrypt each message attachment separately, exposing to the e-mail providers the number of attachments, their filenames, and ciphertext length.