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
