[Top] [All Lists]

BCC (was: Re: V.A. Shiva Ayyadurai: Inventor of e-mail honored by Smithsonian)

2012-02-28 10:48:14

On 2/28/2012 1:02 AM, Paul Smith wrote:
So, apparently he should be remembered for writing something like:

send("From: ");
send (sendersAddress);

(Not to mention that bcc "fields" should not exist anyway - that's the whole 

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 and 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.)



  Dave Crocker
  Brandenburg InternetWorking