Tag: spamfiltering

Mentally modelling filters

When we talk about filters, we often think there is one filter. But, in many cases there are multiple stages of filters, each examining mail in a different way. In deliverability terms the easiest filters to ignore are the individual user filters. Mostly because there’s nothing we can do about those. These are the baysean […]

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Spam makes only 200MM dollars a year

Now, in a new paper in the Journal of Economic Perspectives, Justin Rao of Microsoft and David Reiley of Google (who met working at Yahoo) have teamed up to estimate the cost of spam to society relative to its worldwide revenues. The societal price tag comes to $20 billion. The revenue? A mere $200 million. […]

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Content, trigger words and subject lines

There’s been quite a bit of traffic on twitter this afternoon about a recent blog post by Hubspot identifying trigger words senders should avoid in an email subject line. A number of email experts are assuring the world that content doesn’t matter and are arguing on twitter and in the post comments that no one […]


Filtering adjustments at Hotmail

I’ve been seeing a lot of discussion on various fora recently about increased delivery issues at Hotmail. Some senders are seeing more deferrals, some senders are seeing more mail in the bulk folder. Some senders aren’t seeing any changes. This leads me to believe that Hotmail made some adjustments to their filtering recently. Given some […]


Content based filters

Content based filters are incredibly complex and entire books could be written about how they work and what they look at. Of course, by the time the book was written it would be entirely obsolete. Because of their complexity, though, I am always looking for new ways to explain them to folks. Content based filters […]

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Getting removed from an ISP block

A question came up on a mailing list about how long it typically took to resolve a spam block at an ISP. I don’t think that question actually has a single answer, as each ISP has their own, special, process. ISPA takes 5 minutes. You fill out a form, it runs through their automated system […]


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