Cbl
Help! We're on Spamhaus' list
While trying to figure out what to write today, I checked Facebook. Where I saw a post on the Women of Email group asking for help with a Spamhaus listing. I answered the question. Then realized that was probably useable on the blog. So it’s an impromptu Ask Laura question.
We’re listed on Spamhaus’ list, any advice on how to get off? Our email provider has a plan, just looking for more input.
If you’re on the SBL, there’s a problem (somewhere) with your data collection process. You’re getting addresses that don’t actually belong to your customers / subscribers / whatever.
The fastest way off it to cut WAY back on who you are mailing to. Mail only to addresses you know, for sure, based on activity in the email, want your mail. Then you can start to go through the other addresses and make decisions about how to verify that those addresses belong to the people you think they do.
If you’re at an ESP, do what they tell you to do. Most ESPs have dealt with this before.
One thing to think about, once you get past the crisis stage, is that if you’re on the SBL, it’s likely your delivery is overall pretty bad. These aren’t folks that dramatically list for a single mistake, there’s a pattern. ISPs look at different patterns, but will often find the same answers and delivery will be bad.
It’s important to realize that Spamhaus has 4 or 5 different lists that have different listing criteria. This is for the SBL, there’s also CSS, CBL, PBL, DBL and XBL. They address different problems and have different listing and delisting criteria.
Security issues affect us all
I’ve been talking about security more on the blog. A lot of that is because the security issues are directly affecting many senders. The biggest effect recently has been on companies ending up on the SBL because their signup forms were the target of a subscription attack. But there are other things affecting online spaces that are security related. Right now not much of it is affecting email senders, but it’s good to be aware of.
DDOS attacks
There has been an increase in DDOS attacks against different companies and network. Some of the online game sites have been targeted including EA, Blizzard and others. A group called PoodleCorp is claiming responsibility for those attacks.
Another set of DDOS attacks hit Brian Krebs’ website this week. The site stayed up, but Akamai has told Brian they can no longer host his website. His website is down for now and the foreseeable future.
While this activity doesn’t affect marketers directly, it does tell us that there is active development happening on the less legal side of the internet. The volumes of the recent attacks have sent records. They’re also changing in scope and including new kinds of traffic in an effort to knock sites offline. Even more concerning, they appear to be systematically attempting to discover defenses in order to attack the internet as a whole.
Increase in Spam
Spam has been on the decrease over the last few years. Many of us were treating it as a mostly-solved problem. But a new report from Cisco Talos shows that trend is reversing and spam levels are increasing. Current levels are approaching those last seen more than 5 years ago. Cisco Talos has used a number of different sources of data, all showing an increase in spam directly and indirectly.
How many blocklists do we need?
There’s been a discussion on the mailop list about the number of different blocklists out there. There are discussions about whether we need so many lists, and how difficult the different lists make it to run a small mail system (80K or so users). This discussion wandered around a little bit, but started me thinking about how we got to a place where there are hundreds of different blocklists, and why we need them.
There is a lot of history of blocklists, and it’s long, complicated and involves many strong and passionate personalities. Some of that history is quite personal to me. Not only do I remember email before spam, I was one of MAPS’ first few employees, albeit not handling listings. I’ve talked with folks creating lists, I’ve argued with folks running lists. For a while I was the voice behind a blocklist’s phone number.
The need, desire and demand for different lists has come up over the years. The answer is pretty simple: there are many different types of abuse. One list cannot effectively address all abusive traffic nor have policies that minimize false positives.
Lists need different policies and different delisting criteria. The SBL lists based on volume of email to addresses that are known to have not opted in to receive mail. The PBL lists IPs where the IP owner (usually an ISP) says that the IPs are not supposed to be sending mail by their policy. URIBL and SURBL list domains, not IPs. Some lists have delisting requirements, some let listees remove themselves.
The policies of listing and delisting are not one size fits all, nor should they be.
There are two widely used lists that have significantly different delisting policies: the SBL and the CBL.
The SBL focuses on IP addresses they believe are under the control of or supporting the services of spammers. They measure this by primarily relying on spamtraps, but they also accept forwarded mail from some trusted individuals. Getting delisted from the SBL means explaining to Spamhaus what steps were taken to stop the spam from coming. It’s a manual process with humans in the loop and can require significant business process changes for listees. (We’ve helped dozens of companies resolve SBL listings over the years, contact us if you need help.)
On the other hand, the CBL is a mostly automated list. It lists ources of mail that aren’t real mail servers sending real mail, but are sending a lot of stuff. As they describe it:
CBL issues
I started seeing some folks complain about false CBL listings a few hours ago. I’m now seeing the same folks saying the listings are being removed.
The symptoms look similar to what happened in November (mentioned here), but it appears the CBL team are on top of things and are working to rectify things quickly.
November 2015: The month in email
As we head into the last month of the year, we look back at our November adventures. I spoke twice this month, first at Message Systems Insight in Monterey (my wrap-up post is here) and then with Ken Magill at the at the 2015 All About eMail Virtual Conference & Expo (a short follow-up here, and a longer post on filters that came out of that discussion here.). Both were fun and engaging — it’s always great to get a direct sense of what challenges are hitting people in the email world, and to help clear up myths and misconceptions about what works and doesn’t work in email marketing and delivery. I’m putting together my conference and speaking schedule for 2016 — if you know of anything interesting that should be on my radar, please add it in the comments, thanks!
In industry news, we noted a sharp uptick in CBL listings, and then posted about the explanation for the false positives. Steve wrote about an interesting new Certificate Authority (CA) called Let’s Encrypt, which looks to be a wonderful (and much-needed) alternative for certificates, and I put together some thoughts on SenderScore.
Steve and I did a few posts in parallel this month. First, Steve posted an interesting exercise in SPF debugging. Are you seeing mail from legitimate senders flagged as spam? This might be why. My investigative post was about ISP rejections, and how you can figure out where the block is occurring. In each case, you’ll get a glimpse of how we go about identifying and troubleshooting issues, even when we don’t have much to go on.
We each also wrote a bit about phishing. Steve posted a timely warning about spear phishing — malware attacks disguised as legitimate email from within your organization — and reminds all of us to be careful about attachments. With all of the more secure options for document sharing these days, it’s a lot easier to avoid the risk by maintaining a no-attachments policy in your company. And I wrote about how the Department of Defense breaking HTML links in email to help combat phishing. If your lists include military addresses (.mil), you may want to come up with a strategy for marketing to those recipients that relies less on a clickthrough call to action.
We amused ourselves a bit with a game of Deliverability Bingo, then followed up with a more serious look at the thing we hear all the time — “I’m sure they’ll unblock me if I can just explain my business model.” While an ESP abuse desk is unlikely to be swayed by this strategy, it is actually at the core of how we think about deliverability at Word to the Wise. Legitimate senders have many kinds of lists, many kinds of recipients, many kinds of marketing strategies, and many kinds of business goals. For us to help marketers craft sustainable email programs, we need to understand exactly what matters most to our clients.
What happened with the CBL false listings?
The CBL issued a statement and explanation for the false positives. Copying it here because there doesn’t seem to be a way to link directly to the statement on the CBL front page.
Increase in CBL listings
Update: As of Nov 24, 2015 11:18 Pacific, Spamhaus has rebuilt the zone and removed the broken entries. Expect the new data to propagate in 10 – 15 minutes. Delivery should be back to normal.
The CBL issued a statement, which I reposted for readers that find this post in the future. I think it’s important to remember there is a lot of malicious traffic out there and that malicious traffic affects all of us, even if we never see it.
Original Post from 10am pacific on Nov 24
Mid-morning west coast time, I started seeing an uptick in reports from many ESPs and marketers that they were getting listed on the XBL/CBL. Listings mentioned the kelihos spambot.
CBL website and email back on line
The CBL website is back on line.
It’s possible that your local DNS resolver has old values for it cached. If so, and if you can’t flush your local DNS cache, and you really can’t wait until DNS has been updated then you may be able to put a temporary entry in your hosts file to point to cbl.abuseat.org.
You can get the IP address you need to add by querying the nameserver at ns-2038.awsdns-62.co.uk for cbl.abuseat.org. No, I’m not going to tell you the IP address – if you can’t do a basic DNS query, you shouldn’t be modifying your hosts file and you can just wait a day.
dDOS spreads to the CBL
Spamhaus has mostly mitigated the dDOS against the Spamhaus website and mailserver, but now the CBL is under attack. They have been working to get that under protection as well, but it’s taking some time.
Right now there are no public channels for delisting from the CBL. The Spamhaus Blog will be updated as things change, and I’ll try and keep things updated here as well.
UPDATE: Cloudflare talks about the scope of the attack
The view from a blacklist operator
We run top-level DNS servers for several blacklists including the CBL, the blacklist of infected machines that the SpamHaus XBL is based on. We don’t run the CBL blacklist itself (so we aren’t the right people to contact about a CBL listing) we just run some of the DNS servers – but that means that we do get to see how many different ways people mess up their spam filter configurations.
This is what a valid CBL query looks like: