Right now Delta chat sending messages using field
To: that disclose all groups emails and allows to track relations between emails.
In case of communication with correspondents who using “free” email account from providers such as google, yahoo, etc, email provider can build connection graph between people who using delta.chat. Using
Bcc: field will eliminate such disclosure.
Since the whole purpose of Delta chat is to make communication as private as possible, I suggesting to use
Bcc: field on sending instead of
To: and relations between correspondents, - keep inside of encrypted message as technical field.