Did the algorithm change?

When faced with unexplained deliverability changes one of the first questions many folks ask is “Did the algorithm change.” In many ways this is an meaningless question. Why? Because there are two obvious answers to the question.
A1: Of course it didn’t.
A2: Of course it did.
Both answers are correct, but they’re answering different underlying questions. When we understand how two diametrically opposed answers are both correct, we understand much more about filtering.

What is an algorithm?

When we’re talking about spam filtering the algorithm is the process or rules to follow.

Basically, an algorithm is a computer program that is set up to filter spam to the bulk folder and filter wanted mail into the inbox.  This algorithm doesn’t change. It can’t.
In the case of many (most?) spam filters, the filters incorporate features of machine learning. 
This means the algorithm is constantly changing, learning more and more about what is spam and what is wanted mail based on user interactions.

Algorithms don’t change

Overall, the algorithms don’t change that frequently. They are fed data (lots of data) on a continual basis. They take feedback from recipients (spam / not spam buttons) and developers (new data sets of known bad and known good mail) to learn what good mail looks like and what bad mail looks like. But the underlying code doesn’t change very frequently.

Results change

Machine learning algorithms are only as good as the data they’re fed. In the case of spam filters, the input data is constantly changing. So the output results change. Sometimes an email that was not-spam one day is spam the next because the algorithm caught up with a new threat or new behavior. 

Delivery is still in your control

This machine learning and reliance on end users to help tune filters may make it seem like spam filtering is completely out of the senders’ control. That there is nothing a sender can do to get into or out of the bulk folder. The good news is, the underlying algorithms are pretty simple: wanted mail goes to the inbox, unwanted mail goes to the bulk folder. As with everything, details matter. Senders who are focused on recipients usually don’t have a difficult time reaching the inbox. Companies that focus on themselves and try gimmicks find it much harder to consistently reach the inbox.
 

Related Posts

Inbox rates and conversion rates

Jeanne Jennings published an interesting bit of research on open rates and inbox rates at ClickZ recently. Essentially she looked at two different industry studies and compared their results.
The first study was the Return Path Global Delivery Survey and the second was the Epsilon North American Trend Results. What Jeanne found is that while Return Path shows a decrease in inbox placement, Epsilon is seeing an increase in average open rate.

There are any number of reasons this could be happening, including simply different ways the numbers are calculated. I am not sure it’s just a numbers issue, though. Many of Epsilon’s clients are very big companies with a very experienced marketing team. The Return Path data is across their whole user base, which is a much broader range of marketers at different levels of sophistication.
I expect that the Epsilon data is a subset of the Return Path data, and a subset at the high end at that. It does hint, though, that when the inbox is less cluttered, recipients are more likely to open the commercial mail that does get in there.

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Thinking about deliverability

I was chatting with folks over on one of the email slack channels today. The discussion was about an ESP not wanting to implement a particular change as it would hurt deliverability. It led me down a path of thinking about how we think of deliverability and how that informs how we approach email.
The biggest problem I see is the black and white thinking.
There’s an underlying belief in the deliverability, receiving, and filtering communities  that the only way to affect sending behavior is to block (or threaten to block) mail.

This was true back in the ancient times (the late 90’s). We didn’t have sophisticated tools and fast CPUs. There weren’t a lot of ways to handle bad mail other than to block. Now the landscape is different. We have many more tools and the computing capacity to quickly sort large streams of data.
At most places these days, blocking is an escalation, not a warning shot. Many places rate limit and bulk folder questionable mail as a first strike against problem mail. Sometimes the mail is bad enough to result in a block. Other times, it’s not bad enough to block, so it disappears into the bulk folder.
There’s a corresponding belief in the sending community that if their behavior doesn’t result in blocking then they’re acting acceptably. This isn’t true either. There are a lot of things you can do (or not do) that don’t help delivery, but will actively harm delivery. Likewise, there are things you can do that don’t actively harm delivery, but will help. All of these things add up to reaching the inbox.

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It's not fair

In the delivery space, stuff comes in cycles. We’re currently in a cycle where people are unhappy with spam filters. There are two reasons they’re unhappy: false positives and false negatives.
False positives are emails that the user doesn’t think is spam but goes into the bulk folder anyway.
Fales negatives are emails that the user does thing is spam but is delivered to the inbox.
I’ve sat on multiple calls over the course of my career, with clients and potential clients, where the question I cannot answer comes up. “Why do I still get spam?”
I have a lot of thoughts about this question and what it means for a discussion, how it should be answered and what the next steps are. But it’s important to understand that I, and most of my deliverability colleagues, hate this question. Yet we get it all the time. ISPs get it, too.
A big part of the answer is because spammers spend inordinate amounts of time and money trying to figure out how to break filters. In fact, back in 2006 the FTC fined a company almost a million dollars for using deceptive techniques to try and get into filters. One of the things this company did would be to have folks manually create emails to test filters. Once they found a piece of text that would get into the inbox, they’d spam until the filters caught up. Then, they’d start testing content again to see what would get past the filters. Repeat.
This wasn’t some fly by night company. They had beautiful offices in San Francisco with conference rooms overlooking Treasure Island. They were profitable. They were spammers. Of course, not long after the FTC fined them, they filed bankruptcy and disappeared.
Other spammers create and cultivate vast networks of IP addresses and domains to be used in snowshoeing operations. Still other spammers create criminal acts to hijack reputation of legitimate senders to make it to the inbox.
Why do you still get spam? That’s a bit like asking why people speed or run red lights. You still get spam because spammers invest a lot of money and time into sending you spam. They’re OK with only a small percentage of emails getting through filters, they’ll just make it up in volume.
Spam still exists because spammers still exist.
 

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