I'm not entirely sure, but I _think_ RFC822 allows for an empty
Bcc:-line with only a comment. E.g.:
Bcc: (if you are not contained in the To: header, this is your Bcc copy)
is probably a standards compliant header. I'm not sure if it would help
with the confusion.
The original question was one of privacy, wasn't it? The sender
doesn't want anyone to know whom he's seding email to. No matter
what you do to the email headers and SMTP recipients, the ISP
knows (or could know) that this message was sent to multiple
people. It's a little more safe to send several separate messages,
but they still get this information.
Is this a common problem? I can think of situations where I wouldn't
want the recpeients to know of each other, but I can't think of one
where I'd trust the message to the net att all...
Christer Romson