Robert A. Rosenberg wrote:
At 10:04 -0500 on 03/01/2012, Hector Santos wrote about Re: "proper"
handling of BCC:
There is also the consideration regarding displaying. The MUA may
want to inform the BCC recipient to the privacy nature of the message:
NOTE: THIS IS A BLIND COPY TO YOU. THE OTHER RECIPIENTS LISTED IN THE
TO/CC DISTRIBUTION ARE NOT AWARE OF YOUR RECEPTION OF THIS MESSAGE.
Query - For issuing this message, how do you determine that the
recipient is getting a copy of the message without being listed in a To
or Cc header due to being BCC'ed or being subscribed to a mailing list
(or do you treat a mailing list received copy as a BCC'ed copy)?
Hi Robert,
As John K. alluded to, this would be done at the source - author's MUA
where the message is first created. Perhaps the primary point is that
the sender's distribution list and receiver's reception list is not
based on the RFC5322 headers but rather the SMTP envelope RCPT TO
addresses and these do not need to match what the RFC5322 headers say.
Is the question about how the MUA will do this based on it using
RFC5322 as UI meta when the user is creating the message?
If so, the MUA does not to use RFC5322 for storage data, it could, but
when the SEND button it clicked, it needs to begin to split the blind
recipient streams from the others because its not expected for the MSA
router to do this. It might be possible if we had an SMTP BCC service
extension.
Just winging it, using the following MUA headers:
From:<author-address>
To: <user1-address>
To: <user2-address>
Bcc: <user3-address>
The MUA session might be:
C: EHLO client.domain
S: 250-server.example, Hello client.domain
S: 250-.......
S: 250-BCC
S: 250 HELP
C: MAIL FROM:<author-address>
S: 250 ok
C: RCPT TO:<user1-address>
S: 250 ok
C: RCPT TO:<user2-address>
S: 250 ok
C: RCPT TO:<user3-address> BLIND=NOTE|BCC
S: 250 ok
....
and this basically tells the MSA router to SPLIT this distribution of
the payload into different MTA mail queues.
The BLIND[=options]
NOTE - MSA router MAY add the "This is blind copy" body text
BCC - MSA router MAY add the 5322.BCC for the blind recipient only.
none - MSA router decides.
- For MIME mail, assume BLIND=BCC
- For text/plain simple mail, assume BLIND=NOTE
So if the question is about rendering, displaying, then the BLIND=NOTE
or BLIND=BCC can help. Having 5322.BCC in the blind copy can allow for
supported advanced MUAs to highlight this special private blind copy
to the blind recipient. This may help alleviate concerns that top
posted warning text would interfere with the more complex MIME messages.
--
Sincerely
Hector Santos
http://www.santronics.com
jabber: hector(_at_)jabber(_dot_)isdg(_dot_)net