Lee Jones wrote:

> You are confusing list expansion with CC/BCC.  A CC or BCC address is
> specified in the header portion by the user agent when composing the
> message.  It may be either a single recipient or a list. 
> 
> If a single recipient, then when the user agent hands the message to
> your SMTP client, the SMTP client extracts all addresses from all To:,
> CC:, and BCC: fields appearing in the header.  One connection is made to
> each destination system for each single recipient(*).  During the SMTP
> dialog, the client uses the "rcpt to:" to specify the recipient on the
> SMTP server system.

I'm not sure I understand you correctly, but it seems you are not talking
about a general standard here, but rather about how a specific
implementation of email user agent and smtp client works.

In many cases, what you seem to call user agent and what you seem to call
smtp client are both parts of one program. In these cases, there isn't
really a BCC header field that would indicate a BCC recipient to the smtp
client -- this is done in a different way, internally to the program. 

Since it is exactly the purpose of the "B" in BCC that the recipient is
/not/ listed in any headers, I also assume that your smtp client strips out
such a header line before sending the message if it receives one with it
from your user agent. 

In any case, the scenario you describe here is probably not a standard, and
it is probably not even very common, at least WRT the BCC field (among
email GUI applications, that is, which are probably used by a large
majority of email users).

Gerhard
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