For what it's worth, I've been in touch with 4 or 5 of my mail admin
counterparts at other companies regarding the Exchange mis-configuration.
I approached them in a congenial manner and with two key points I was able
to persuade them to change their Exchange configuration:
A. The configuration change takes 1 minute.*
B. The change does not require a reboot.*
C. The change should *not* affect internal network NT name services*
D. The change is in their best interest because it makes their configuration
standards-compliant and more compatible with security conscious MTA peers.
So it's been a little more effort to communicate with the other companies,
but it's paid off so far.
* (FYI, the fix is to change the TCP/IP hostname properties in Windows NT
server 4.0)
- David
> -----Original Message-----
> From: Richard.Hall [mailto:richard.hall@ingenta.com]
> Sent: Thursday, June 26, 2003 9:50 AM
> To: exim-users@???
> Subject: [Exim] Exchange, HELO and underscores
>
>
> Yes, I know it's an old chestnut, but I still have to fight
> this battle
> occasionally. This time the opposition is resisting, and I
> need chapter
> and verse, moral support, advice, and anything else that's going.
>
> I'm running Exim 4.12 on Solaris 8. A misconfigured Exchange server is
> sending me a HELO name with an underscore in it.
>
> I used to reject at HELO time (default behaviour), but after
> investigating
> this particular sender, and following advice to others that I
> have seen on
> this list, I now have in my configuration
>
> # Many broken Exchange servers use '_' in the HELO data. If
> we reject at
> # HELO time, they very often fail to deal with the problem; plus they
> # cannot mail postmaster here (yippee!) to discuss the
> problem. So rather
> # than using acl_smtp_helo (which doesn't even exist in the version of
> # Exim I'm currently running!), we allow it through the HELO
> by specifying
>
> helo_allow_chars = _
>
> # and then check it later, in acl_smtp_rcpt, _after_ we have
> got past the
> # postmaster exception.
>
> ... and later ...
>
> accept local_parts = postmaster : abuse
> domains = +local_domains
>
> # Now enforce the HELO checks which we skipped earlier
>
> deny message = Rejected because of unacceptable syntax in \
> HELO/EHLO name:\n\
> $sender_helo_name\n\
> This is commonly associated with
> misconfigured mail \
> software;\n\
> see RFC2821 section 4.1.2 for legal
> domain syntax.\n\
> For assistance please contact
> postmaster@$domain
> log_message = invalid HELO syntax $sender_helo_name
> condition = ${if match {$sender_helo_name} {_} {1} {0}}
>
>
> In exim_rejectlog I see
>
> 2003-06-26 15:14:30 H=(iri_pdc.iriinc.org) [207.224.21.210]
> F=<xxxx@???> rejected RCPT <yyyy@???>: invalid
> HELO syntax
> iri_pdc.iriinc.org
>
> and (I assume) they got the 'message' as above, though there are
> indications that Exchange kindly failed to pass it on intact
> to the user,
> much as one would expect of Exchange :-(
>
> I now quote from the fax (yes, really) they have sent us
>
> ...
> The recipient name is not recognized [OK, my fault for
> rejecting RCPT]
> [rather than HELO, I
> guess. ]
> ...
> 550 For assistance please contact postmaster@???
>
> Oh good, at least part of my message got through; shame they
> ignored the
> postmaster bit! It goes on (transcription errors notwithstanding) as
> follows
>
> "Hello,
>
> I was talking to my consultant yesterday who saw your e-mail
> about why I
> could not send to you and he said your message basically is
> asking us to
> change our "name" so your server can recognize it. But I
> hesitate to do
> that because you are the only one to whom I cannot send to.
> And we've had
> this "name" for a while, and I used to be able to send to you until
> recently. Changing our "name" complicates things for us.
>
> ....
> "
>
> What can I do? I can either give in (not keen), or
>
> a) quote RFC2821 section 4.1.2 at them till I'm blue in the face
> b) swear blind that nothing has changed (except that I now reject them
> later than I used to) - but why do they claim it has
> changed recently
> - or was it different on Exim 3, which one of my other MX's was
> running?
> c) tell them that lots of other people would reject their
> mail - is that
> true?
> d) tell them how to reconfigure Exchange to behave properly -
> except that
> I don't know how - so does anyone else know how to do it?
>
>
> Any and all suggestions welcome.
>
> TIA,
> Richard Hall
>
>
> --
>
> ## List details at
> http://www.exim.org/mailman/listinfo/exim-users Exim details
> at http://www.exim.org/ ##
>
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