Thinking about filters

Much of the current deliverability advice focuses on a few key ideas:

  1. Authenticate your mail with SPF, DKIM and DMARC
  2. Use a dedicated IP.
  3. Monitor delivery.
  4. Clean your data.

All of these things are absolutely things you should be doing, but senders can do all these things and still have cruddy delivery. These things are great and can help your mail deliver better. But they’re not enough to get mail into the inbox.

As I think about email filters I can put them in some different broad categories based on the email types they target.

  • Safety filters – block phishing and malware
  • Unsolicited filters – block mail that looks like it’s unsolicited
  • Unwanted filters – block mail that is unwanted by the recipient

Safety filters are pretty self explanatory. They use different signals like source IP, links, and virus signatures to block mail. Some safety filters are about protecting the infrastructure, so they act on senders that open too many connections, or send non-RFC compliant mail or act in ways that are not well-behaved.

Unsolicited filters have their own signals they use to determine if a message is unsolicited. These include a lot of the things we talk about in delivery. Things like spam complaints, bounces, and spamtrap hits are all things that indicate recipients never opted in to receive a particular email.

Unwanted filters use some of the same signals as unsolicited filters, the difference between unsolicited email and unwanted email is somewhat subtle. Signals for unwanted filters are the things we describe as engagement metrics. When emails are read and saved and moved between folders that tells the ISP these mails are wanted. Emails that are deleted without opening are likely unwanted.

Understanding what kind of mail filters are targeting helps drive what types of fixes we do. If the problem is our users don’t want the mail then removing bounces isn’t going to affect the signals driving the filter.

On the flip side, if the problem is the mail looks unsolicited because it has too many dead addresses and hits spamtraps, we can sometimes fix them using the same techniques we use for addressing unwanted filters. When we limit sending to people who have opened and engaged with the messages, we’re removing the addresses that signal the email is unwanted and the email is unsolicited.

Filters like Spamhaus focus on unsolicited emails. That’s why they focus on making sure that senders have permission rather than focusing on engagement metrics.

Understanding what type a mail a filter is attempting to protect users from is crucial for solving delivery problems.

 

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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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New Spamhaus lists

Spamhaus announced today they are publishing two new BGP feeds: Extended DROP and the Botnet C&C list. These lists are intended for use inside routers in order to stop all traffic to or from listed IP addresses. This is a great way to impact botnet traffic and hopefully will have a significant impact on virus infections and botnet traffic.
In other news I’ve been hearing rumbling about changes at Yahoo. It looks like they have changed their filters and some senders are feeling lots of pain because of it. It looks like senders with low to mid range reputations are most affected and are seeing more and more of their mail hit the bulk folder. This afternoon I’m hearing that some folks are seeing delivery  improvements as Yahoo tweaks the changes.

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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.

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