The Spam That Got Through

All of my company’s inbound and outbound email goes through a security service that scans for spam and viruses. From time to time I get an email from someone saying that they got a message that they consider spam. I see that as a good sign. Here’s why:

Spam filters are machines, with some human input to fine-tune the filter criteria, doing the best job they can. The algorithms are ever-improving, but they’re still just computer programs.

Also, spam filters read mail, not minds—some of what they see looks enough like legitimate email that they are allowed to pass through. If I, a human, were reading our inbound email feed, I probably would allow many of the “spam” messages, too. It’s not possible for man or machine to know the mind of every recipient, how they would classify every message they receive.

And the humans that fine-tune the filter criteria tend to err on the side of caution: a false positive—deleting a sales lead, a message from an attorney, etc.—is far more costly an error than a false negative—the spam that got through.

According to the reports I get from our spam filtering service, 89% of our inbound email is deleted as spam, 1% is quarantined as likely spam, and the remaining 10% is delivered as normal email. That translates to about 2.7 million spam messages a year that never hit our inboxes. Under that kind of barrage, I’m surprised anyone finds it surprising when a single unwanted message sneaks through.

That’s what I consider a good sign: if end users are surprised when they get a single spam, it means our filters are doing a pretty darn good job.

I hope that puts things in perspective.


Author: Jeff Garretson

Husband, father. Data Scientist. Explorer of Powerful Ideas. Faith and Reason in one package.