Since 2005 I've been running a proxy mailing list where users sign up to receive new proxy sites by email. (Proxy sites are sites for getting around Internet blocking software; most proxy sites that you can find through Google are already blocked by major blocking programs, which is why you would sign up to receive new ones by email, to use them until they get blocked as well.) In all that time, we've followed what are considered best practices for email newsletters: every new subscriber is sent a confirmation message by email, and they have to reply to that message, confirming that they really want to subscribe to the emails, before being added to the list. This practice, known as "verified-opt-in," is considered the gold standard for responsible emailing, since it ensures that everyone on your list actually wants to get your emails. (It also ensures that if you accuse an email publisher of spamming because you received their unwanted emails, they can't say, "Oh, one of your friends must have added you" — since if they're using verified-opt-in like they're supposed to, your friends can't add you.) I'm front-loading a lot of information here, although if you saw the words "Spamhaus errors" in the title, you may recognize the technique of literary foreshadowing being employed.
Despite conforming to verified-opt-in standards, the proxy emails have at times been blocked by spam filters used by Hotmail, Gmail, Yahoo Mail, AOL Mail, and various other systems. However, last month was the first time that an incorrect blacklisting caused the domains themselves to be disabled, so that the sites disappeared from the Internet entirely.
On September 17th I registered 10 new .info domains through NameCheap, set up new proxy sites at each of those domains, and mailed each site to 1/10th of our proxy mailing list. (Sending new sites only to a subset of the list makes it harder for blocking software companies to join the list and find all new sites as soon as they're released.) All seemed to be going well until October 2, when subscribers started telling me that they were getting "host not found" errors when trying to reach the sites. I tried the sites myself, found that they were indeed inaccessible, and spent about an hour testing for various problems with DNS servers and domain record settings, before logging in to NameCheap and seeing a message next to each of the new domains saying "domain locked due to illegal activity; please email email@example.com." (NameCheap being a reseller for the domain registrar eNom.)
So I sent eNom an email and followed up with a phone call to see if they could speed things up, since complaints kept pouring in from users that the sites were unreachable. eNom said that the domains had actually been suspended by Afilias, the company that handles all .info domain registrations no matter who you buy the domain from, and eNom was in the process of talking with Afilias. So I called Afilias myself to ask about getting the domains unlocked, but they refused to talk to me and said that they could only respond to inquiries from eNom. This, of course, is ridiculous — if someone notifies you that you or your company has made a error, you can investigate the issue no matter who brings it to your attention — and especially in cases where you're literally accusing someone of unspecified "illegal activity," you should bend over backwards to respond to any indication that you might have made a mistake. But they refused to do anything, so I waited for a response back from eNom.
A day and a half ticked by, with emails continuing to come in from our users wondering why the domains had disappeared, until finally eNom forwarded me a response from Afilias saying that two of my ten domains ("drybook.info" and "rootface.info") had been blacklisted by the UK-based organization Spamhaus on their Domain Block List. Spamhaus operates several different alleged "spam" blacklists, and claims that the DBL is a list of domains found in spam messages. The DBL FAQ says that it is "built predominantly using automated spamtraps and email flow monitoring" and "has many checks to prevent legitimate domains being listed," even going so far as to call it a "zero false-positive" list.
Even though only two of the ten domains that I had registered that day had been blacklisted by Spamhaus, Afilias had responded by disabling the entire group of ten domains that I had bought at the same time.
Now here's where I caught a bit of a break: It turns out I was able to get the domains instantly removed from the DBL by entering them in a form on the Spamhaus site and clicking a button, which took me to a page saying:
DBL removal successful
The domain was successfully removed from the DBL. Please allow 30 minutes for servers around the world to update their data. Please note that the domain will be re-listed if malicious activity is detected in the future.
Although, even this easy part of the process didn't inspire much confidence. Not that I wanted Spamhaus to make it harder for me to de-list by domain names, of course, but if you really think your blacklist is 100% accurate, why would you let anyone get any domain removed at any time just by submitting it in a form? In fact, this would seem to give an advantage to spammers over regular website owners — because a spammer, who knows about blacklists and would find it worthwhile to game the system in his favor, would be more likely to know about the Spamhaus DBL and the form for getting their domains de-listed. Whereas for a regular non-spamming website owner, it would take far more time to find out that their domains had been de-activated, that the de-activation had occurred because of an incorrect Spamhaus listing, etc.
Once the listing had been removed, I emailed eNom, who emailed Afilias, who eventually re-activated the domains after a few more hours. But the traffic never returned to the levels that it had been at before the domains were deleted, as most of our users had apparently concluded that the sites had been blocked or taken offline.
Spamhaus did not respond to requests for comment on this story. In fact, Spamhaus does not give you a way to contact them if you have been wrongly blacklisted — their "contacts" page redirects you to the "Blocklist Removal Center" if your domain is blocked, but that only leads you to the automated removal tools, not a way to contact the organization. I did email their "Press Office" email address, on the grounds that I was writing an article for Slashdot in addition to being a wrongly blacklisted domain owner, but didn't get an answer.
So I have no idea what will happen with the next group of domains that I send out to our proxy list. If Spamhaus signed up one of their "spamtrap" email addresses to our mailing list, then presumably any domain mentioned in a message sent to that email, will get automatically blacklisted (even though of course since they signed up the email address to our mailing list, that means it's not spam). If that happens, the entire next batch of domains might get disabled by Afilias as well.
Meanwhile, Spamhaus continues to claim that the DBL is a "zero false-positive" list. I don't know how many other false positives are on the list or how many domains have been abruptly disabled as a result, but if it's this easy to get incorrectly blacklisted, my money is not on "zero."