Message hash fields MTA option

Message archiving and hashing MTA options:  (list of header names)
This option takes either a comma-separated list or space-separated list of up to thirty-two known (to the MTA) header field names, each with or without a trailing colon (and intervening spaces are okay too). The default is: Message-id:,From:,To:,Cc:,Bcc:,Resent-message-id:,Resent-From:,Resent-To:, Resent-Cc:,Resent-Bcc:,Subject:,Content-id:,Content-type:,Content-description: (The Content-type: and Content-description: here are those from the top or outer MIME level of the message.)

See Message identifier generation for a discussion of use of this option in the content of message archiving.

See also:
 * Message identifier generation
 * Message archival and hashing MTA options