> On 28. Dec 2023, at 22:17, Martijn van Duren <opensm...@list.imperialat.at> 
> wrote:
> On Thu, 2023-12-28 at 20:05 +0100, Kirill A. Korinsky wrote:
>> Example of software is sieve: as far as I know it doesn't support matching 
>> case insensitive strings.
> Does this currently pose a problem for anyone? If not I don't see a
> reason to make a new release for it.

Well, right now it should be written in sieve like this:

> if anyof(header :is "X-Spam" "yes", header :is "X-Spam" "Yes") {
>   fileinto :create "Junk";
> }

a bit ugly but I agree that it's not enough for a release.

>> I've read the code and I agree that implementing whitelist can be quite 
>> tricky.
>> Anyway, I do have one idea: let introduce flag -i (inverse). It should 
>> remove X-Spam: yes if matches with -m.
> Why? What does this bring? Why do you need this?

Right now I'm making a kind of the experiment: living without any statistical 
analyser for my mail.

The hypotesa: usual mail traffic for family mail server is too small to make 
statistical analyser like spamassasian useful by impact of mails.

So, I'm testing another approach: only DNSBL which delivers everything that is 
matched into Junk folder.

Long story short I do have the following configuration:

 - NiX Spam and blocklist.de <http://blocklist.de/> at spamd
 - smptd configuration:

> filter dnsbl proc-exec "filter-dnsbl -m \
>        all.spamrats.com \
>        bip.virusfree.cz \
>        bl.mailspike.org \
>        bl.spamcop.net \
>        bl.spameatingmonkey.net \
>        cbl.abuseat.org \
>        dnsbl-1.uceprotect.net \
>        dnsbl.dronebl.org \
>        mail-abuse.blacklist.jippg.org \
>        psbl.surriel.com \
>        rbl.0spam.org \
>        truncate.gbudb.net \
>        zen.spamhaus.org \
>        XXX.combined.mail.abusix.zone \
>        "
> filter dnswl proc-exec "filter-dnsbl -m \
>        XXX.white.mail.abusix.zone \
>        "
> filter "senderscore" proc-exec "filter-senderscore -junkBelow 70"
> listen on egress inet4 port smtp tls pki mx1.catap.net \
>        filter { "rdns", "fcrdns", dnsbl, dnswl, "senderscore" }

- and sieve script to move mail:

> if allof(
>   anyof(header :is "X-Spam" "yes", header :is "X-Spam" "Yes"),
>   not header :is "X-Spam-DNSBL" "Listed at white.mail.abusix.zone") {
>     fileinto :create "Junk";
> }

this works like a charm, really.

The idea of both changes to use white lists to remove X-Spam: yes from both 
negative filters.

>> But I haven't see any easy way to implement it for non -m case.
>> During read the code of this filter I guess I've found third point which I'd 
>> like to raise: filter fails in the case when one of provided DNSBL returns 
>> error.
>> Shall it continue?
> If a filter (or the intermediate DNS layer) returns an error we are in
> limbo. If we accept the mail, but it's listed we're probably delivering
> spam; if we reject the mail we're very likely to drop legit mail. Both
> are undesirable. Failing the message asking to try again later seems the
> safest option to me.

I see your point.

My point: user may wait messages and to be very nervous if it delayed for a 

Important message means something like a ticket for a train in 5-15 minutes or 
something like that.

And here DNS seems like a single point of failure.

I think that it should be configurable by bypass DNS error by probability of 
delivering spam instead of delaying everything.

wbr, Kirill

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