> Jon Rust <[EMAIL PROTECTED]> wrote:
> > I agree with most of what you said here Dave, but I'd have to say
> > that rejecting mail with envelope sender domains that don't exist is
> > a good thing (either an A or CNAME record, or an MX). If for no other
> > reason, you can't bounce back to them. I don't consider this aspect
> > an arms race with spammers, just common sense. You give me a false
> > from address, I reject your mail.
>
> Except you're supposing that if a domain is valid, you can resolve it.
They
> aren't the same thing. I see the daily mail logs here every day, and we
always
> have a few legitimate mails which are rejected by a receiver doing this;
> the problem is, their DNS is down, or their resolver is broken, or their
> BIND has decided to take a field day. Result? They reject our legitimate
> mail.
Well there are other ways to test if a domain *at least* exists. You can
check it with whois.
OK this is not *the* good answer either, but at least it gives you an good
indication that the domain name is potentially working...
The problem with spam is that there is no reliable way to split spam from
legitimate mail. If you try to filter-out spam, you will always end-up
filtering out proper mail as well. The key is to try to keep track as much
as possible of what is accepted and what is rejected.
Also the tolerable lost email / killed spam ratio is somewhat a personal
decision...
Patrick.
