On Mon, Mar 06, 2000 at 03:29:06PM +0100, Markus Stumpf wrote:
> Hoi folx,
>
> just had a discussion with a support person. Their MUA is not deleting
> Bcc: Lines from the header.
Then it's the villain.
> They claim it's within the repsonsibility of the MTA to look at the
> headers and "do the right thing".
Only if the MTA is being used as an MUA. This is the case with sendmail
and exim, for example, where the same binary serves as the daemon as
well as the command line MUA. If the MTA is invoked on the command line
with the -t option, it should strip the Bcc: header. Otherwise, if it
receives the message via SMTP, it should not.
> IMHO this is wrong. However all I could find about it was RFC1123
> section 5.2.1, which says the MUA should construct envelope fields for
> the SMTP protocol.
You can use the logic in this to deduce who is responsible for what.
1. An SMTP server is supposed to use the MAIL FROM: as the sender
address and the RCPT TO:'s as the recipients. It's _not_ supposed to
look in the headers for any sender/recipient info.
2. In that case then, if the SMTP server is not going to look at the
headers, it should not be bothered about stripping any Bcc: fields.
3. Therefore, it is up to the MUA to strip the Bcc: field, and use its
contents in its SMTP dialogue with the mail server to supply the RCPT
fields.
There is some description of how the Bcc: field is to be handled in RFC
822, but it's very ambigious. Here's the relevant section:
4.5.3. BCC / RESENT-BCC
This field contains the identity of additional recipients of
the message. The contents of this field are not included in
copies of the message sent to the primary and secondary reci-
pients. Some systems may choose to include the text of the
"Bcc" field only in the author(s)'s copy, while others may
also include it in the text sent to all those indicated in the
"Bcc" list.
At the end of the day, Bcc: is a feature of the mail client, and the MTA
does not need to bother with it. Take for example, the case where an MUA
sends a message to other users on a system by directly writing messages
in the other users' mailboxes (eg. Pegasus running in Netware). No MTA
is involved there, and if the MUA doesn't strip the Bcc:, it has only
itself to blame.
--
See complete headers for more info
