Having looked at the log file in more detail this is what was happening:
Message gets redirected by Outlook/Exchange to hotmail address, so gets sent
to Exim.
Exim attempts to deliver to hotmail but delivery fails due to account
unavailable/mailbox full. Exim returns the message to Outlook (with <> in
header)
which promptly forwards it again....
By looking at the message size each time Outlook forwards it, I find that
the size
remains pretty much the same, so the headers aren't accumulating, due, no
doubt to
Outlook ever so kindly stripping all those nasty (i.e. non-MS) internet
headers, which means
the loop won't break on the number of Received headers, nor will it break on
a size limit.
I then thought "why not use the system filter to freeze anything for
hotmail.com and have
it auto-thawed every X hours". Unfortunately, even with auto_thaw set to 6h
I found this morning
that a test message I submitted yesterday (about 18h ago) was still frozen.
I'm obviously missing
something somewhere.
Here is what I had in the system filter:
if $h_to contains "hotmail.com"
then
freeze "Hotmail destination frozen"
endif
This successfully managed to block all mail to hotmail (as well as an
incoming mail which happened to be Cc'd to a hotmail address).
I thought, perhaps, the message was immediately getting frozen each time
auto-thaw kicked in, so this is what I have in the filter at the moment:
if ($h_to contains "hotmail.com" and $h_from contains "uce.ac.uk") and
first_delivery
then
freeze "Hotmail destination frozen"
endif
Any suggestions?
Paul Walsh
Senior Systems Programmer, Information Services,
University of Central England, BIRMINGHAM B42 2SU, UK
Tel: +44 (0)121 331 5708 Fax: +44 (0)121 356 2875
> -----Original Message-----
> From: Philip Hazel [SMTP:ph10@???]
> Sent: Wednesday, December 22, 1999 10:23 AM
> To: Chris Knipe
> Cc: Exim Users
> Subject: Re: [Exim] Stopping loops
>
> On Tue, 21 Dec 1999, Chris Knipe wrote:
>
> > Account A forwards mail to Account B, ASWELL as spam@???
> > Account B forwards mail to Account A, ASWELL as spam@???
>
> > Or
> > is it perhaps allready protected?
>
> If it is forwarding as implemented by Exim, the loop gets broken when
> the maximum number of Received: headers is reached.
>
> If it is "forwarding" by creating a new message each time, the loop will
> break if the size increases and there is a limit. But hey, if you want
> to attack servers this way you can just write a program that spits out
> mail. You don't have to be so elaborate.
>
> --
> Philip Hazel University of Cambridge Computing Service,
> ph10@??? Cambridge, England. Phone: +44 1223 334714.
>
>
>
> --
> ## List details at http://www.exim.org/mailman/listinfo/exim-users Exim
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