[Gllug] OSS Spam filtering, virus scanning email solutions

[Andy Smith]

On Wed, Jan 03, 2007 at 12:03:37PM +0000, John G Walker wrote:
> On Wed, 03 Jan 2007 11:46:03 +0000 Matthew Thompson
> <matt.thompson at actuality.co.uk> wrote:
> > Got a bit of a puzzle - we already have plenty of anti virus and anti 
> > spam in place on our company's email system but it seems that our use
> > of the Spamhaus SBL+XBL feed is annoying some journalists who insist
> > on using dodgy russian ISPs.

You said they were being blocked because the IPs they were using were
previously owned by infected machines.  They should not be directly
relaying mail from IPs that are handed out to end-user systems.
They should[1] be using their ISP's mail relays.

If that proves problematic then I would suggest setting up SMTP AUTH
so that people you employ can use your mail servers wherever they
may be located.

> You don't just have to use dodgy ISPs to get on a blacklist from
> Spamhaus, Spamcop or the like. These guys also blacklist people they
> don't approve of (eg wrong politics).

DNSBLs vary wildly in their goals, sizes, efficacy and standards of
operation and to roll them all together like this in order to make
some blanket statement is disingenuous at best.  In particular the
service offered by Spamcop is so vastly different to that offered by
Spamhaus that even mentioning them in the same sentence is rarely
useful.

About the only blanket statement that I feel is appropriate is that
it is rarely sensible to outright block email based on DNSBL
results.

Cheers,
Andy

[1] Not interested in an argument about whether blocking
    dynamic/end-user IPs is appropriate, just acknowledging that it
    happens a lot in the real world.
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