On 2/28/2012 1:02 AM, Paul Smith wrote:
So, apparently he should be remembered for writing something like:
send("From: ");
send (sendersAddress);
send(CRLF);
(Not to mention that bcc "fields" should not exist anyway - that's the whole
point)
BCC is more interesting than usually appreciated, IMO.
At the architectural level is the distinction between a construct limited to the
author's MUA, versus something with end-to-end properties.
As an MUA construct it lets an author note recipients that won't be indicated to
other recipients. Constrained to a UI mechanism, it's not really part of
Internet Mail architecturally. Its contents get added to the transport protocol
list (RFC5321.rcptto). The result looks rather like what a mailing list posts.
The tendency for MUAs has been to do only the above and thereby create only a
single submission posting. To do more requires at least one additional posting.
With separate postings, the MUA can submit variants of the email object.
What some MUAs do is a single additional posting, where the email object
contains an empty rfc5322.bcc header field. This can serve to alert the bcc
recipient that they are, in fact, a bcc recipient. One could have a receiving
MUA handle such a message differentially, though I believe none do.
I've also seen an added posting per bcc recipient, where the individual bcc
recipient's address is in their copy of the message.
There's a variant I did, but can't remember whether I got it done to the
original MH (by Bruce Borden and later taken over by Marshall Rose at UC Irvine)
or to MMDF while I was at UDel.
Anyhow, the enhancement was to prevent a Bcc recipient from unintentionally
sending a reply that copied the primary recipients. (This happens when a bcc
recipient does a Reply All.)
As I recall, for the bcc posting, I modified the rfc5322.to and rfc5322.cc
header field names to be: [To]: and [cc]:
Visually, this could look quite natural to the recipient, but of course the
Reply command wouldn't see them.
(the next person responsible for that code removed the feature.)
d/
--
Dave Crocker
Brandenburg InternetWorking
bbiw.net