> the MTA's and other mail servers add header fields tha not only uniquely identify sender and recipient but details about the conversation and attachments.
Well this is misleading. While is true that PGP has non-ecrypted header files, MTAs/servers cannot add significant details about conversation, because they do not have any other information that is not already publicly known.
Some non-encrypted details about conversation (e.g. In-Reply-To header) is unencrpypted, but added by originating mail client, not server. Subject is also well-known to be unencrypted.
Attachments, their content, types, filenames and lengths are all parts of messaged data (in OpenPGP) and are therefore encrypted.
Well this is misleading. While is true that PGP has non-ecrypted header files, MTAs/servers cannot add significant details about conversation, because they do not have any other information that is not already publicly known.
Some non-encrypted details about conversation (e.g. In-Reply-To header) is unencrpypted, but added by originating mail client, not server. Subject is also well-known to be unencrypted.
Attachments, their content, types, filenames and lengths are all parts of messaged data (in OpenPGP) and are therefore encrypted.