Re: Filtering out empty messages as spam

[Christian Andersson <ca...@ofs.no>]

After taking a look at most of these empty messages, it certainly looks 
like they all comes from dhcp-pools (adsl/dsl/etc home computers)  so it 
certainly looks like I could try to filter them out directly, the 
question then comes to, how big impackt would that be on legitimit mail?

at the moment I don't think there would be any problems, but for 
example, I was thinking of setting up my own mail-server at home also, 
and there I have ADSL where I get the ip from a dhcp pool, and I would 
by introducing a filter for this cut of my own home-mailserver from the 
corporate mail server.

if it just was my mail-server that would be no big problem filtero\ing 
out so that messages from that one would come through, but it might not 
be just my mail-server.

anyway, HOW do I set up this type of filtering?

/Christian

Noel J. Bergman wrote:
> There is no such matcher as yet, but you could easily write one.
> 
> Note that adsl-66-72-203-112.dsl.clevoh.ameritech.net ([66.72.203.112]) is a
> DHCP user.  Many mail servers ban e-mails sent directly from DHCP pools, by
> using DNS RBLs.
> 
> 	--- Noel
> 
> 
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RE: Filtering out empty messages as spam

["Noel J. Bergman" <no...@devtech.com>]

> I was thinking of setting up my own mail-server at home also, and
> there I have ADSL where I get the ip from a dhcp pool, and I would
> by introducing a filter for this cut of my own home-mailserver from
> the corporate mail server.

You could use your corporate mail server as a gateway, and add specific
access for your home system.  If you don't do that, and even if you allow
DHCP e-mail so that you aren't cutting off your own home system, it won't
matter when you send e-mail directly from home to other systems that are
blocking DHCP pools.  Most DNS RBLs include a zone for tracking DHCP pools,
and almost every e-mail admin I know is blocking DHCP pools.

There is almost no reason to accept e-mail from DHCP connected systems
coming from the USA.  However, apparently some European ISPs do not provide
e-mail gateways.  [They are not blocked for the @apache domain because of
concerns about ASF community members who are still sending through DHCP
systems, particularly in Germany.]

I'm planning to finally finish what might be the first piece of code I ever
started working on for James: a country matcher.  I had stopped because I'd
hoped that we'd have better matcher configuration support, but for the first
cut, I'll just have to parse a string.

> HOW do I set up this type of filtering?

See the examples for the InSpammerBlacklist matcher.  That is another
matcher that could use a bit of extension.  I hope to replace it with an
InDNSRBL matcher that uses the DNS directly, allows specific zones to be
specified, and records the associated TXT record.

	--- Noel


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