How our spam filter works

I got lucky in April 2004, when Gmail had just launched, and I snagged one of the first invitations (I didn't work at Google at the time, but had a few friends who did). One of the first things I noticed was the spam filter. I had used another webmail service for the previous few years and was used to seeing spam in my inbox every day. With Gmail, I almost never did, and what's more, I didn't have legitimate email ending up in the spam folder (I eventually just stopped looking there). This is still true today, even though I've had my email address for 3+ years and use it on many sites around the web.

Now that I work on Gmail, not only do I keep an eye on my personal email, but I also monitor Gmail-wide stats which rigorously measure how our spam filters are doing. And despite an increase in spam targeted at Gmail, we're keeping more unwanted messages out of your inbox than ever before:


We get mail and read posts all the time from people who've noticed these results:

• "None of my real emails have slipped into the spam folder and I remember only one spam reaching my inbox in the period I've been using Gmail. Spam is the bane of the Internet and it is refreshing to see Gmail put up such a good fight against it." - Eric, who wrote into our support team


• "I've been using Gmail as my main email account ever since I started receiving an average of 2,500 emails a day...of which 70 percent are...personal health products, free software, and more! If not for this wonderful spam filter of Gmail, I'd have to spend 48 hours sitting in front of my mail 24/7 just to keep up!" - Nicholas, CNET blogger

To help explain how our spam filter works, we put together a video starring some of our anti-spam engineers. Enjoy!