On Mon, May 14, 2001 at 07:07:51PM +0530, Suresh Ramasubramanian wrote:
> * [Frank Elsner on 14/05/01 13:23 +0200]
>
> > Currently I have
> > headers_sender_verify = yes
> > headers_checks_fail = yes
> > and a now list owner complains about refused messages with unresolvable
> > domain in the "From: " line of a messages sent via his mailing list.
>
> RFCs were not invented to be read by morons, as someone said. You are
> perfectly free to reject mail from unresolvable domains, and this guy is
> nitpicking.
He is free to do anything, of course. But in this case:
Someone behind a firewall sends a message to the mailinglist I am
administering. The sender happens to have an incorrect From: header. A
user in the TU-Berlin.DE domain is a subscriber to the list, hence a copy of
the post is sent to him. But the message bounces back to the mailinglist
manager (ezmlm) which then sends a probe to the user to see if all is well
with the *TU-Berlin.DE* address. And this happens every time this user with
bad From: posts to the list.
The filtering of From: headers happens on a server that only relays the
message to the end user. It is another passage from rfc2821 (note this time
the MUST NOT)
As discussed in section 2.4.1, a relay SMTP has no need to inspect or act
upon the headers or body of the message data and MUST NOT do so except to
add its own "Received:" header (section 4.4) and, optionally, to attempt
to detect looping in the mail system (see section 6.2).
>
> > When RFC 822 format [7, 32] is being used, the mail data include the
> > memo header items such as Date, Subject, To, Cc, From. Server SMTP
> > systems SHOULD NOT reject messages based on perceived defects in the
>
> He's confusing the header from with the envelope from, which is what exim
> filters on.
Where ? The envelope sender address was perfectly legal; only the From:
address filtering is under scrutiny.
Last remark: some people on purpose give invalid From: address when they
post to mailinglists from fear that when the list is archived, their address
gets exposed to spammers.
Mate
---
Mate Wierdl | Dept. of Math. Sciences | University of Memphis
