Don't spam filter your role accounts

A variety of “amazon.com order confirmations” showed up in my inbox this morning. They were quite well done, looking pretty close to real Amazon branding, so quite a few people will click on them. And they funnel people who do click to websites that contain hostile flash apps that’ll compromise their machines (and steal their private data, login and banking credentials then add them to botnets to attack other sites and so on).
Not good. Just the sort of urgent, high-risk issue that ISP abuse desks really want to hear about. I sent email about it to the ISPs involved, including a copy of the original email. One of them went to iWeb, a big (tens of thousands of servers) hosting company.
This was the response:

<abuse@noc.privatedns.com>: host mott.privatedns.com[174.142.252.34] said: 554 rejected due to spam content (in reply to end of DATA command)

That’s iWeb’s main abuse address for their address space, as registered with ARIN. They even have a comment in their network registration that says “Please use abuse@noc.privatedns.com for abuse issues”.
For email related abuse (spam, malware email, botnets, phishing, viruses, …) almost all valid, actionable abuse reports will include a copy of the email involved. And that’s exactly the sort of content that content-based spam filters do their best to block. That means that putting content-based spam filters on your abuse or security role addresses will prevent you seeing most reports about abusive traffic coming from your network.
There are some companies that have an intentional policy of rejecting most spam reports sent to them so that their abuse metrics look better, and they don’t have to pay for abuse desk staff to handle the high volumes of abuse reports their customers provoke. “Mistakenly” putting spam filters on their abuse alias is one way of doing that – others include using non-standard abuse aliases, demanding reports come in only via web forms, requiring abuse reports be sent in non-human-writable formats while discarding all others, and many more. If you don’t want to behave responsibly it’s easy enough to dodge those reports.
Legitimate companies really want to know about abusive traffic sooner rather than later, so they can shut it down and mitigate the damage as quickly as possible. Email systems are complex, though, and it’s quite easy for an upgrade to spam filtering at a companies main mailserver to mistakenly by applied to abuse@ and security@ aliases – especially when spam filtering or email services are outsourced. And if you’re a company that uses dozens of domains it’s easy to lose track of where mail to abuse@ some of those domains ends up.
If you’re responsible for email, abuse or security at your organization it’s worth occasionally checking that your role accounts actually work. Find yourself a fairly obvious bit of spam, then forward it to your abuse@ role address (with a sentence or two telling your abuse desk that you’re just testing, and can they reply to your mail so you know they received it).
Real spam sent directly to abuse@ role addresses can be a severe problem, but content-based filtering is not the way to deal with it. One approach that we suggest to our Abacus users is to prioritize reports that mention a URL or an IP address on your network, so that legitimate, actionable reports will “bubble up” above any spam.

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Changes at Gmail

As I’ve said before, I can usually tell when some ISP changes their filtering algorithm because I start getting tons and tons of calls about delivery problems at that ISP. This past month it’s been Gmail.
There have been two symptoms I’ve been hearing about. One is an increase in bulk folder delivery for mail that previously was reliably hitting the inbox. The other is a bit more interesting. I’ve heard of 3 different mailers, with good reputations and very clean lists, that are seeing 4xx delays on some of their mail. The only consistency I, and my colleagues at some ESPs, have identified is that the mail is “bursty.”
The senders affected by this do send out mail daily, but the daily mail is primarily order confirmations or receipts or other transactional mails. They send bi-weekly newsletters, though, exploding their volume from a few tens of thousands up to hundreds of thousands. This seems to trigger Gmail to defer mail. It does get delivered eventually. It’s frustrating to try and deal with because neither side is really doing anything wrong, but good senders are seeing delivery delays.
For the bulk foldering, Bronto has a good blog post talking about the changes and offering some solid suggestions for how to deal with them. I’m also hearing from some folks who are reliable that Gmail may be rolling back some of the bulk foldering changes based on feedback from their users.
So if you’re seeing changes at Gmail, it’s not just you.

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Where do you accept reports?

One of the things that is most frustrating to me about sending in spam reports is that many ESPs and senders don’t actively monitor their abuse address. A few months ago I talked about getting spam from Dell to multiple email addresses of mine.
What I didn’t talk about was how badly broken the ESP was in handling my complaint. The ESP was, like many ESPs, an organization that grew organically and also purchased several smaller ESPs over the course of a few years. This means they have at least 5 or 6 different domains.
The problem is, they don’t effectively monitor abuse@ for those different domains. In fact, it took me blogging about it to get any response from the ESP. Unfortunately, that initial response was “why didn’t you tell us about it?”
I pointed out I’d tried abuse@domain1, abuse@domain2, abuse@domain3, and abuse@domain4. Some of the addresses were in the mail headers, others were in the ESP record at abuse.net. Three of those addresses bounced with “no such user.” In other words, I’d tried to tell them, but they weren’t accepting reports in a way I could access.
Every ESP should have active abuse addresses at domains that show up in their mail. This means the bounce address domain should have an abuse address. The reverse DNS domain should have an abuse address. The d= domain should have an abuse address.
And those addresses should be monitored. In the Dell case, the ESP did have an active abuse@ address but it was handled by corporate. Corporate dropped the ball and never forwarded the complaint to the ESP reps who could act on the spam issue.
ESPs and all senders should have abuse@ addresses that are monitored. They should also be tested on a regular basis. In the above case, addresses that used to work were disabled during some upgrade or another. No one thought to test to see if they were working after the change.
You should also test your process. If you send in a complaint, how does it get handled? What happens? Do you even have a complaint handling process outside of “count and forward”?
All large scale senders should have appropriate abuse@ addresses that are monitored. If you don’t, well, you look like a spammer.

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Email filters

What makes the best email filter? There isn’t really a single answer to that question. Different people and different organizations have different tolerances for how false positives versus false negatives. For instance, we’re quite sensitive to false positives here, so we run extremely conservative filtering and don’t block very much at the MTA level. Other people I know are very sensitive to false negatives and run more aggressive filtering and block quite a bit of mail at the MTA level.
For the major ISPs, the people who plan, approve, design and monitor the filters usually want to maximize customer happiness. They want to deliver as much real mail as possible while blocking as much bad mail. Blocking real mail and letting through bad mail both result in unhappy customers and increase the ISP’s costs, either through customer churn or through support calls. And this is a process, filters are not static. ISPs roll out new filters all the time, sometimes they are an improvement and sometimes they’re not. When they’re not, they’re pulled out of production. This works both for positive filters like Return Path and negative filters like blocklists.
Then there is mail filtering that doesn’t have to do with spam. Business filters, for instance, often block non-business mail. Permission of the recipient often isn’t even a factor. Companies don’t often go out of their way to block personal mail, but if personal mail gets blocked (say the vacation plane ticket or the amazon receipt) they don’t often unblock it. But when you think about why a business provides email, it makes perfect sense. The business provides email to further its own business goals. Some personal usage is usually OK, but if someone notices and blocks personal email then it’s unlikely the business will unblock it, even if the employee opted in.
In the case of email filters, the free market does work. Different ISPs filter mail differently. Some people love Gmail’s filters. Other people think Hotmail has the best filtering. There are different standards for filtering, and that makes email stronger and more robust. Consumers have choices in their mail provider and spamfiltering.

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