Thanks, so it seems likely that Gmail->Yahoo email is in plaintext. That Google will "do TLS" is ambiguous. Are we sure Yahoo attempts TLS on their SMTP-connec

Thanks, so it seems likely that Gmail->Yahoo email is in plaintext. That Google will "do TLS" is ambiguous. Are we sure Yahoo attempts TLS on their SMTP-connect to Google's MX? It seems unlikely if they don't support it on their own receives, and also unlikely that Gmail would reject all non-TLS SMTP. If so, NSA wouldn't need Google or Yahoo's private key to record the plaintext of all email between them. And if the Google<->Yahoo interchange is representative, plenty of other email to or from Gmail will be similarly transparent.