On Thu, Mar 18, 2010 at 06:43:29PM +0000, Kay wrote:
> I often see mail being rejected by recipient servers because
> an IP in a Received From header is blacklisted somewhere.
>
> This strikes me as a rather bad practise, since it undermines
> the whole idea of SMTP authentication.
>
> Here's an example reject:
>
> 550 5.7.1 This system has been configured to reject your mail.
> An IP address (xx.xx.xx.xx) found in the message's 'Received:'
> headers is listed by the lookup site 'sbl-xbl.spamhaus.org.'.
>
> xx.xx.xx.xx is the client's IP, a regular dynamic IP on a
> broadband connection. Which shouldn't have any relevance.
I have mixed feelings about this. Yes, it is a misuse of a DNSBL, but
if the IP is on SBL, indeed, the sender is probably a spammer, even
in the unlikely event that the mail itself is not spam. I'd be fine
with rejecting that. I don't do this, but I think it's reasonable.
(I'd test it out before going live with it.)
When it gets to XBL, things are less clear. If the sender is the
person responsible for the spamming host, the sender does need to
fix the problem. But many times the sender is an innocent bystander
(bypasser) using a poorly-run public hotspot or hotel connection. I
lived in an XBL-listed hotel[1] for two months once! No point in
complaining to the manager (I actually did try!) because it's all
contracted out to lousy companies. They can't do anything even if
they can understand what you're saying (which is of course not
likely; I failed to explain it to my hotel manager.) So there, I'd
err on the side of caution.
When it gets to PBL it is insanely, maddenly, stupid.
> To make matters worse, the offending recipient site does not accept
> mail for abuse/postmaster or any of the usual aliases.
>
> How do you engage hosts like these to resolve such issues?
Noel's workaround is good. OTOH, sites that are stupid get what the
postmaster deserves. It's too bad that there are so many poorly-run
mail hosts. All we can do is commiserate and suggest you nominate
these sites for rbl-ignorant.org.
[1] I ran into that problem early on and fixed the issue myself by
relaying my outbound mail through my VPN to my own mail host.
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