Re: [Exim] MAIL FROM:<> -> block mail from non compliant MTA…

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Author: Marc MERLIN
Date:  
To: Robert Lister, Dave C.
CC: exim-users
Old-Topics: [Exim] MAIL FROM:<>
Subject: Re: [Exim] MAIL FROM:<> -> block mail from non compliant MTAs
On Sun, Aug 26, 2001 at 12:21:15PM +0100, Robert Lister wrote:
>
> Hmm.
>
> It seems that a lot of people (including spammers themselves) are
> rejecting bounces addressed from "MAIL FROM: <>"
>
> "501 bogus MAIL FROM"
>
> I want to deal with this somehow.


That's easy:
1) Point the affected people to:
http://marc.merlins.org/netrants/nullenvelope.txt

2) Install my patch which make exim complain with an explicit error message
when you use SMTP callback:
ftp://ftp.valinux.com/pub/people/merlin/exim-3.31-woody-99.1/exim-callback_and_gooderrmsg.diff

it outputs:
string_sprintf("response from %s [%s] after \"MAIL FROM: <>\" was \"%s\".
This does not help fight spam effectively, breaks RFCs, and prevents you
from getting bounces so we can't accept mail from you",

> Is it possible to configure exim not to use MAIL FROM:<>,
> but use, say, postmaster (not strictly obeying the protocol I know)


While being misguided for a few minutes, I wrote a patch to do that, and
then realized the obvious, which is that you can create mail loops if you do
so (especially if you do this in SMTP callback).

So, the answer to your problem is to start using SMTP callback with my
patch, and the affected mail servers will not be able to Email you at all
anymore until they fix their mail.
After that, you won't have to worry about not being able to bounce back to
them since you won't have to carry their mail in the first place :-)

Marc
-- 
Microsoft is to operating systems & security ....
                                      .... what McDonalds is to gourmet cooking


Home page: http://marc.merlins.org/ | Finger marc_f@??? for PGP key