Boris <[EMAIL PROTECTED]> writes:
> Thats all to check for valid ip/dns of the sender.
What are `valid IP addresses'? I assume you expect a check if the
given sender domain has a valid MX or A record. I think it's a bad
idea to do such checking for several reasons:
1. I costs time and other resources. SMTP latency is high and this approach
increases it by orders of magnitude. In other words - it decreases
throughput.
2. It doesn't help against spammers.
Like all other technical approaches it is subject to the anti-fax effect
(look at the qmail list archive to see what this means:
http://www.ornl.gov/its/archives/mailing-lists/qmail/1999/01/msg00777.html)
The approach only forces spammers to use resolveable domain names with all
the bad consequences for the owners of that domains.
3. It's often plain wrong implemented - about half of the double bounces I have to
manage at work result from brain dead anti-spam patches on sendmail boxes
that don't let through the empty envelope sender.
A quarter of double bounces results from boxes that check the envelope sender
and generate permanent errors when their BIND server is overloaded.
I personally tend to block all of such hosts until they fix their broken setup
but many of them are important partners and clients of our company. My boss
even doesn't allow me to tell them that they are doing something wrong.
Shitty politics ...
I agree with Dan Bernstein that the only ways to fight SPAM are legal actions
against them and transferring the costs for email to the sender.
> Is there an option for qmail? I only found some ugly
> patches/scripts/workarounds?
There are patches that do this. If they are ugly, I don't know.
Regards, Frank
