What is a dot-zero listing?

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Some email blacklists focus solely on allowing their users to block mail from problematic sources. Others aim to reduce the amount of bad mail sent and prefer senders clean up their practices, rather than just blocking them wholesale. The Spamhaus SBL is one of the second type, using listings both to block mail permanently from irredeemable spammers and as short term encouragement for a sender to fix their practices.
All a blacklists infrastructure – and the infrastructure of related companies, such as reputation monitoring services – is based on identifying senders by their IP addresses and recording their misbehaviour as records associated with those IP addresses. For example, one test entry for the SBL is the IP address 192.203.178.107, and the associated record is SBL230. Because of that they tend not to have a good way to deal with entities that aren’t associated with an IP address range.
Sometimes a blacklist operator would like put a sender on notice that the mail they’re emitting is a problem, and that they should take steps to fix that, but they don’t want to actually block that senders mail immediately. How to do that, within the constraints of the IP address based blacklist infrastructure?
IP addresses are assigned to users in contiguous blocks and there’s always a few wasted, as you can’t use the first or last addresses in that range (for technical / historical reasons). Our main network consists of 128 IP addresses, 184.105.179.128 to 184.105.179.255, but we can’t put servers on 184.105.179.128 (as it’s our router) or 184.105.179.255 (as it’s the “broadcast address” for our subnet).
So if Spamhaus wanted to warn us that we were in danger of having our mail blocked, they could fire a shot across our bow without risk of blocking any mail right now by listing the first address in our subnet – 184.105.179.128 – knowing that we don’t have a server running on that address.
For any organization with more than 128 IP addresses – which includes pretty much all ISPs and ESPs – IP addresses are assigned such that the first IP address in the range ends in a zero, so that warning listing will be for an address “x.y.z.0” – it’s a dot-zero listing.

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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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Spamhaus rising?

Ken has a good article talking about how many ESPs have tightened their standards recently and are really hounding their customers to stop sending mail recipients don’t want and don’t like. Ken credits much of this change to Spamhaus and their new tools.

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Marketing to businesses

“If you do stupid things, you’re going to get blocked,” says Jigsaw CEO Jim Fowler in an interview with Ken Magill earlier this week.
Jigsaw is a company that rewards members to input their valuable business contacts. Once the addresses are input into Jigsaw, they are sold to anyone who wants them. Jigsaw gets the money, the people providing information get… something, the people who provided business cards to Jigsaw members get spammed and the people who downloaded the lists get to deal with a delivery mess. Sounds like a lose for everyone but Jigsaw.
Except that now Jigsaw is listed on the SBL for spam support services. Well, that’s going to cause some business challenges, particularly given how many companies use the SBL as part of their filtering scheme.
It’s hard to think of a situation where I would appreciate someone I gave a business card to providing my information to a site that then turns around and lets anyone download it to send email to. I know, I know, there are a million companies out there I’ve never heard of that have The Product that will Solve All my Problems. But, really, I don’t want them in my work mailbox. The address I give out on my business cards is, for, y’know, people to contact me about what I’m selling or to contact me about things they’ve already purchased from me. That address is not for people to market to. I have other addresses for vendors, and even potential vendors, to contact me.
Jigsaw clearly facilitates spam to businesses by collecting email addresses and then selling them on. This is a drain on small businesses who now have inboxes full of valuable offers to wade through. Perhaps their stint on the SBL will make them reconsider their spam support services.
HT: Al

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