Hello all
Anyone got any ideas on the following? I'm sure it's a standard
problem with a standard solution but I can't see anything obvious in
the documentation and would rather ask for ideas before experimenting
on a live system.
On our internal mail hub binnen.mail.nl.demon.net , we have got a list
set up to reach a group of customers, web-klanten@??? . This
morning I found mail to the list looping. A customer on the list had
got a mailer set up such that when it received mail To:
web-klanten@??? it thought that the mail wasn't for it, so it
forwarded (relayed) it to web-klanten@??? ... with the From:
field still set to the original sender within Demon NL, who is
authorised to send to the list ... so binnen.mail thought that this
was a valid posting and...
Yes, the ideal solution would be to get the customer to configure
their mailer sensibly (and not run an open relay) but this sort of
thing is bound to happen again. I'm not sure whether to (a) rewrite
the To: field to be something invalid (but that would mean changing
the configuration every time a new list is set up, to add a new
rewriting rule); (b) rewrite the From: field to something not
authorised to post to the list; (c) trap mail to closed lists by
sending host as well as by actual sender; (d) do something with
Received: fields so that if the mail has been round once already, it
is rejected. I can't see how to do (b) sensibly (ie only rewrite the
From: field for list mail, nor how to do (c) or (d) at all. There is
probably a better solution that I haven't thought of.
Configuration details (director):
gesloten_lijsten:
driver = forwardfile
domains = nl.demon.net:binnen.mail.nl.demon.net
require_files = "/var/exim/gesloten-lijsten/${local_part}: \
/var/exim/gesloten-lijsten/${local_part}.afzenders"
senders = lsearch;/var/exim/gesloten-lijsten/${local_part}.afzenders
file = /var/exim/gesloten-lijsten/${local_part}
no_check_local_user
forbid_pipe
forbid_file
skip_syntax_errors
syntax_errors_to = listmaster@???
errors_to = ${local_part}-request@???
ie taken more or less directly from the example on the web site, where
the list.afzenders file contains the people aoutorised to post to the
list. Thus a new list can be created simply by putting the two files
in place without any configuration changes.
Gyan Mathur, Sysadmin, Demon Internet Nederland.
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