On Tue, 27 Oct 1998 020shero@??? wrote:
> I am running exim1.92 on solaris2.6.
> My configuration etries to stop spam is as follows:-
>
> sender_reject_recipients = dbm;/opt/VCSexim/etc/spam-sender
> sender_host_reject = partial-dbm;/opt/VCSexim/etc/spam-host
>
> where spam-host and spam-sender are files containing domain names and
> addresses that need to be blocked.
> This works fine, but entries that are in upper case or have some
> uppercase letters in them seem to come through. They don't seem to be
> blocked at all.
Upper/lower case shouldn't be a problem for sender_host_reject, since
host names (and domain names in general) are case-insensitive. Exim
should be lower casing the host name before trying to look it up in your
DBM file.
However, the RFCs about mail specify that local parts *are* case
sensitive. So when Exim is looking up the sender address in
sender_reject_recipients, it has to do so using the caseful form of the
sender address. (In principle, "user@domain" and "USER@domain" might be
different people. Silly, I know, but that's the rule. It causes a lot of
grief.)
If you are using exim_dbmbuild to create your DBM files, then you need
to use the -nolc option to stop it lowercasing the keys when it builds
the /opt/VCSexim/etc/spam-sender file.
This doesn't of course, help when you block "User@domain" and mail comes
in with the sender "USERR@domain".
This is a long-standing problem to which I don't really have a good
answer. However, there is something you can do. If you convert to using
an @@-style lookup for sender_reject_recipients (see section 7.14), then
(1) The domain is looked up in a case-insensitive manner.
(2) You can use case-insensitive regular expression matches for the
individual local parts if you want to.
--
Philip Hazel University of Cambridge Computing Service,
ph10@??? Cambridge, England. Phone: +44 1223 334714.
--
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