On Thu, Jan 17, 2002 at 11:44:00AM -0500, Fox wrote:
> If I am getting spam with "Undisclosed recipients" in the header, how would
> the mail server (qmail) have known who to deliver it to had it not been
> spam? Or does the server (qmail) just choose to log messages with bcc's as
> undisclosed recipients even though it knows who the message is to?
Much like in real life, email has an envelope and a message. The envelope is
the only piece used to say where mail is coming from and where it is going
to. The message header's "To" and "Cc" header are actually quite irrelevant.
I forget where the "undisclosed recipients" part gets added, I think it's the
sender's MUA, but I wouldn't swear to it.
The reason a Bcc is a Bcc is because the first MTA gets the Bcc: message
header, adds it to the list of envelope recipients, then strips it from
the message. At this point, there's no way to find out who the message is
sent to from the recipient-side (or anywhere past the first MTA actually.)
As an example, here's a typical SMTP session to explain envelope versus
message:
220 eclectic.kluge.net ESMTP Sendmail; Thu, 17 Jan 2002 12:11:38 -0500
HELO localhost
250 eclectic.kluge.net Hello localhost [127.0.0.1], pleased to meet you
MAIL FROM:<[EMAIL PROTECTED]>
250 2.1.0 <[EMAIL PROTECTED]>... Sender ok
RCPT TO:<[EMAIL PROTECTED]>
250 2.1.5 <[EMAIL PROTECTED]>... Recipient ok
DATA
354 Enter mail, end with "." on a line by itself
To: (undisclosed recipients)
From: Some Evil Spammer? <[EMAIL PROTECTED]>
X-Any-Other-Header: I want in the message...
It really doesn't matter what goes here, this is the message body.
.
250 2.0.0 g0HHBoZ03257 Message accepted for delivery
QUIT
221 2.0.0 eclectic.kluge.net closing connection
> Are all "Undisclosed recipient" type emails spam?
100% of them? No. But I don't know what the actual percentage is. What is
the likelihood that someone will send a message to a list of Bcc addresses
and not put in an address in the To/Cc header?
If there isn't one already, this might not be a bad low-score rule for SA.
<shrug>
--
Randomly Generated Tagline:
Foul temptress. I'll bet she thinks Ziggy's gotten too preachy, too!
-- Homer Simpson
The Last Temptation of Homer
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