Re: [Exim] Error from Exchange server

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Author: Alan J. Flavell
Date:  
To: Giuliano Gavazzi
CC: Richard Welty, exim list
Subject: Re: [Exim] Error from Exchange server
On Sat, 8 Feb 2003, Giuliano Gavazzi wrote:

> > From our rejection log, I can assure you that many of these defective
> >domains are spammers and other kinds of email abuser. It really would
> >not be a good idea to accept the lot of them without further protest.
>
> oh yes? (In short, you will not necessarily avoid spam by being
> strict as the HELO error can be ignored).


Extract from our ACL for RCPT TO (modulo line wrapping, and I
suppose it might be more complicated than it need be...):

# Be polite and say HELO. Reject anything from hosts that havn't given
# a valid HELO/EHLO to us.
 deny condition = ${if \
   or{{!def:sender_helo_name}{eq{$sender_helo_name}{}}}{yes}{no}}
          message = RFCs mandate HELO/EHLO before mail can be sent.


> [ti:~] xfhjsf% telnet mailhost 25
> Trying x.y.t.w...
> Connected to x.y.t.w.
> Escape character is '^]'.
> 220 x.y.t.w ESMTP Exim 4.12 Sat, 08 Feb 2003 19:10:38 +0000
> helo a_b.ntl.com
> 501 Syntactically invalid HELO argument(s)
> mail from: test @hotmail.com
> 250 OK
> rcpt to: fsdlfjfds @humph.com


To which yours said

> 250 Accepted


Ours would say at this point:

550 RFCs mandate HELO/EHLO before mail can be sent.

> As you can see a real spammer can just
> ignore this error. Indeed they do,


Indeed, they do ignore this error. But we don't!

cheers