Brief DBL false positive


Spamhaus are rolling out a new subzone of the DBL, for domains whose webservers have been compromised and used to host spam landing pages, often via mass compromises of their management control panels. There was a brief mistake that caused all of .net to be listed in the new subzone, meaning that mail sent with URLs in it that used hostnames in .net may have been rejected or spam-foldered by early adopters or careless users of the DBL.
If you’re using one of the reputation services that wraps many different sorts of listing in a single zone, differentiating between different listing reasons by return code, you should be aware of what all the subzones are and what listings of each type mean. Unless the blacklist operator has a published policy about what sort of sublists might be added in the future, you should never configure your mailservers to take action on any returned value, rather you should check for specific return values and ignore any response that you don’t explicitly intend to use.
If your MTA supports it, logging unrecognized responses and alerting based on them is a good idea – both so you know when a new category is added, and so you know if you’ve been blocked from accessing the blacklist, or the blacklist has been shut down and is listing the entire Internet. It’s not unusual for blacklists to see very high query volumes for months or years after they’ve been shut down, presumably from users who are using the data as part of  a scoring system and who haven’t noticed that it’s no longer providing any useful data.
 

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ROKSO

ROKSO is the Register of Known Spamming Operations. It is a list of groups that have been disconnected from more than 3 different networks for spamming. ROKSO is a little bit different than most of the Spamhaus lists. The listings themselves talk more about the background of the listees and less about the specific emails that are the problem.
Many ISPs and ESPs use ROKSO during customer vetting processes.
Networks can be listed on ROKSO without any mail being sent from those networks. These listings are as much about just categorizing and recording associated networks as they are about blocking spam.
Spamhaus does not accept delisting requests for ROKSO records. In order to be delisted from ROKSO there must be a 6 month period with no spam traceable to the ROKSO entity. After that 6 months the listee can petition for a review of the record. If the spam has stopped their record is retired.
In my experience there is often a lot of research put into each ROKSO record and not all that information is made public.
The only time a record is changed is if Spamhaus is convinced they made a mistake. This does happen, but it’s not that common. Given the amount of research that goes into a ROKSO record, there is a fairly high burden of proof to demonstrate that the information is actually incorrect.
It is possible to get delisted off ROKSO. In all of the cases I know about, the listed entity either got out of email altogether or they radically changed their business model.

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Links: September 24, 2012

Last week Return Path announce a new set of email intelligence products. One of their new products offers customers the chance to actually see how (some subset of) their customer base interacts with mail directly. It moves beyond simply looking at probe mailboxes and actually looks inside the mailbox of recipients.
Spamhaus has listed bit.ly on the Domain Blocklist (DBL) for allowing spammers to abuse their redirector service. Spammers have been abusing bit.ly for a while, and I’m a little surprised it’s taken so long for a listing to happen. Steve wrote a post last year about URL redirectors and offered suggestions on what to do to avoid blocking problems when using a URL shortening service.
Real Insights has a very interesting post on why it should be “hard” to subscribe to your mailing list. There are also a number of good suggestions about the subscription process itself. Definitely worth a read.

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Winning friends and removing blocks

I do a lot of negotiating with blocklists and ISPs on behalf of my clients and recently was dealing with two incidents. What made this so interesting to me was how differently the clients approached the negotiations.
In one case, a client had a spammer slip onto their system. As a result the client was added to the SBL. The client disconnected the customer, got their IP delisted from the SBL and all was good until the spammer managed to sweet talk the new abuse rep into turning his account back on. Predictably, he started spamming again and the SBL relisted the IP.
My client contacted me and asked me to intercede with Spamhaus. I received a detailed analysis of what happened, how it happened and how they were addressing the issue to prevent it happening in the future. I relayed the info to Spamhaus, the block was lifted and things are all back to normal.
Contrast that with another client dealing with widespread blocking due to a reputation problem. Their approach was to ask the blocking entity which clients they needed to disconnect in order to fix the problem. When the blocking entity responded, the customer disconnected the clients and considered the issue closed. They didn’t look at the underlying issues that caused the reputation problems, nor did they look at how they could prevent this in the future. They didn’t evaluate the customers they disconnected to identify where their processes failed.
The first client took responsibility for their problems, looked at the issues and resolved things without relying on Spamhaus to tell them how to fix things. Even though they had a problem, and is statistically going to have the occasional problem in the future, this interaction was very positive for them. Their reputation with the Spamhaus volunteers is improved because of their actions.
The second client didn’t do any of that. And the people they were dealing with at the blocking entity know it. Their reputation with the people behind the blocking entity was not improved by their actions.
These two clients are quite representative of what I’ve seen over the years. Some senders see blocking as a sign that somehow, somewhere there is a flaw in their process and a sign they need to figure out how to fix it. Others see blocking as an inconvenience. Their only involvement is finding out the minimum they need to do to get unblocked, doing it and then returning to business as usual. Unsurprisingly, the first type of client has a much better delivery rate than the second.

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