dch3 said:
If an email is sent out with receipients in the BCC field and one of the
BCC'd people click 'REPLY TO ALL', will their response be sent *EVERYONE*
listed in the TO, CC, and BCC fields?
We've got a debate going on in the office about it.
How is an recipient going to reply to anyone when no one is listed as a
recipient? That's the point of the Bcc header: no recipient know what
other, if any, recipient got the same message (for those that were
originally listed in the Bcc header).
Delivery of e-mail does NOT use the To, Cc, and Bcc "headers". These
are just *data* within the body of the message and the e-mail client
decides whether or not to include them. According to RFC 2822, the To
header must appear once and only once, the Cc header may appear zero or
one times, and the Bcc header may appear zero or one times (but really
should NEVER be added by the e-mail client; otherwise, the purpose of
Bcc is thwarted). When you receive an e-mail where Bcc was used by the
sender, none of the recipients in the Bcc field will be listed in the
copy of the message you get. The e-mail client compiles an aggregate of
recipients from the To, Cc, and Bcc *fields* (shown in the GUI of your
e-mail client) to create a list of recipients. For each recipient in
that aggregate list, a RCPT-TO command is sent from the e-mail client to
the mail server. For N recipients (across the To, Cc, and Bcc fields),
there will be N RCPT-TO commands. The recipient never gets to see the
list of commands the sender's e-mail client sent to their sending mail
host. After all RCPT-TO commands are sent, a single DATA command is
sent that contains the *data* of the message. That data will include
whatever the e-mail client puts inside the message. That usually
includes the To and Cc "headers" (the header section is first, delimited
by a blank line, followed by the body of the message). The e-mail
client should NOT add the Bcc header to the data of the message. If the
sending mail server sees a Bcc header in the message's data, it should
strip it out. If the receiving mail server sees a Bcc header in the
received e-mail then it should strip it out.
So you, as the recipient, NEVER get to see the list of RCPT-TO commands.
For a proper e-mail client (or for mail hosts that should strip out the
header), you will not see any recipients that were in the Bcc header.
So just how are you going to reply to a non-existent list of recipients
(if all of them were in the Bcc field used by the sender in their e-mail
client)? Reply To All will only work against the list of recipients
that are known, and those would only be those in the To and Cc headers.
