Re: [Exim] Getting rejects for sending Spam - Sender set wro…

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Auteur: dman
Date:  
À: exim-users
Sujet: Re: [Exim] Getting rejects for sending Spam - Sender set wrong
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On Fri, May 31, 2002 at 05:53:53AM -0400, Anita Lewis wrote:
| On Thu, May 30, 2002 at 04:34:08PM -0500, dman wrote:
| > --
| > On Thu, May 30, 2002 at 03:27:53PM -0400, ajlewis2@??? wrote:
| > | I am writing this from webmail at work; so the header will not show what I'm
| > | talking about here.
| > |
| > | When I send a message, Sender: says ajlewis2@sidekick.
| >
| > The Sender: header doesn't mean anything. It's purely informative for
| > people who want to check whether or not a mail has been forged. (of
| > course, it is in no way conclusive)

|
| Are you saying that the Sender: is not the reason why I am getting the
| rejects from a couple of ISPs?


It shouldn't be, though perhaps a deformed Sender: header would fail
exim's syntax checks (which I have enabled).

| I'm wondering why my email doesn't go through when I send it from my
| computer, but it does go through when I send it directly from my
| ISPs mailserver using ssh. I figured that was because the Sender:
| in the second instance is a valid domain name. I think the error I
| got in the first instance was that ajlewis2@sidekick was not a valid
| email address.


Can you show us the exact error message (all of it)?
Even before seeing the error message, I'll take a guess as to what is
wrong.

Here's my guesses/assumptions :
    "sidekick" is the name of your machine
    "ajlewis2" is your username
    the 127.0.0.1 line in /etc/hosts looks like this
            127.0.0.1  sidekick  localhost


What happens is that exim calls a library function to find out what
FQDN it is. Unfortunately (at least on my GNU system) it returns the
unqualified name that appears first on the 127.0.0.1 line in
/etc/hosts. So exim thinks your FQDN is "sidekick". When the user
"ajlewis2" sends a message that defines a From: header, here's what
happens :

    1)  if ajlewis2 is not a "trusted" user (shouldn't be) then a
        Sender: header is added containing "username@host".  If you
        were forging From: headers while ssh-ed in to your ISP, they
        could trace it with that header.  If your "forged" From:
        header is legitimate, no one will care about the Sender:
        header.


    2)  exim sets the envelope sender to "user@host", in this case
        'ajlewis2@sidekick'.  The envelope is different from the
        message contents.


An SMTP conversation with the server that rejected your mail would
look something like this :

<<< 220 (server banner)
>>> EHLO sidekick

<<< 250 Hello sidekick (whatever text they return)
>>> MAIL FROM: <ajlewis2@sidekick>

<<< 550 Invalid sender address.

*This* is the data you need to change.

There are 2 ways you can change it.  Do you have a FQDN?  If so, just
change the hosts line to read
    127.0.0.1  THE.FQDN sidekick localhost
if not, then create an entry in /etc/email-addresses like this
    ajlewis2: ajlewis2@???


so that exim can rewrite your local-but-invalid-on-the-internet
address to your correct Internet address.

HTH,
-D

--

A man of many companions may come to ruin,
but there is a friend that sticks closer than a brother.
        Proverbs 18:24


GnuPG key : http://dman.ddts.net/~dman/public_key.gpg

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