At 10:38 AM 4/8/99 -0400, Francoise Becker wrote:
>On 8 Apr 99, at 0:04, Stan Ryckman wrote:
>
>> >The probes do look to the user exactly like a regular list posting.
>>
>> Well, not quite... the first time I received one, it sneaked right
>> past my procmail filters which sort mailing lists into folders, etc.
>
>I suppose I ought to have been more precise: the RFC822 mail headers
>look exactly the same, and most standards compliant mail programs
>(which excludes CC:mail) will show the mail like any other list mail.
>
>I'm curious what field you are filtering on. The ONLY difference is the
>RFC 821 (SMTP) MAIL FROM: (Which some mail servers will turn into
>a Return Path: mail header, so that's a slight difference, but that is
>usually hidden from the reader). Is that what you're filtering on?

Sort of, but not exactly.  The "procmail" I mentioned operates in a
UNIX environment.  It is typically either run as the mail delivery
agent (MDA) or invoked by it.  Generally mail handed to UNIX MDAs
is given a "pseudo" header "From " (followed by a space, not a colon)
often described in discussions as From_ to avoid confusion with From:.
Here's a typical one (the indentation is mine):

    From [log in to unmask] Thu Apr  8 22:00:40 1999

This contains the RFC821 MAIL FROM as well as the date "delivered" (in the
local time zone, presumptiously not identified).  Both can be useful.

Sometimes the address is also put into a Return-Path: header (as you
mentioned), particularly if it might subsequently undergo POP or IMAP
processing which will destroy the From_.

Procmail's filtering is quite flexible; my "fixed" recipe to handle
probes for SPAM-L is now just:
    # Forward the SPAM-L list; the .* is for PROBEs
    :0
    * ^From owner-spam-l.*@
    ! [log in to unmask]
The fix was just to add the .* which means "zero or more of any character".
I have no need for mail from that list to sit at the UNIX account, so it's
forwarded elsewhere where I'll sift through it if time allows.  For lists
tricky to identify after POPping, I have procmail run formail to add
my own header I can look for later (typically, I copy the From_ into an
Old-From_: header in RFC 822 format).

(I use procmail for a lot of things.  To stay on topic, it's also quite useful
for handling bounces from my list and the other various reports.)

The derivatives of SMTP MAIL FROM are much better than anything else for
identifying mailing list mail.  Headerfields like To: and Cc: are useless
(suppose I Cc'd you on this post; both copies you get would have the
same ones).  At least until RFC 2369 (hope that's the right number :) is widely
adopted, the uses of Sender:, X-Mailing-List:, Resent-Sender:, etc. by various
types of lists remains not at all consistent.

Yes, in the UNIX mail clients I'm familiar with, the From_ line is generally
hidden from display except in see-all-the-headers mode or in passing the
message to a pipe; however, the line *is* used for sorting by date received.

Sorry if I ramble too much; I'll shut up now.  :-)

Cheers,
Stan