After Jake Ludington released an article on how Google uses Email and spam detection in search ranking, I went looking for proof one way or another.
Matt Cutts responded to the post saying that "Google doesn’t use email as an indicator in search rankings." But it wouldn’t be the first time Matt told me something that turned out to be not true, so I broke out the Google phone numbers I had, and started dialing, not just people who work there currently and would know better to talk to me, but those who don’t work there currently and would be more willing to talk. I didn’t have to ask too many people before I found people who were quick to point out that Google uses data from Gmail in LOTS of places, and some of those places are search.
While talking with a former employee, he pointed out that Google Patented the idea of using email as a positive indicator in search in 2007, but had filed the patent in 2005. The patent describes how Google would use the number of times a Blog was forwarded to people as an indicator of it’s importance and therefore its rank. This would be possibly the anti-thesis of what Jake was seeing, but had it been implemented would indicate that Matt was wrong that Google does use email as an indicator, or did at one point. Even Google’s link spam detection patent includes references to checking email data to be used as a negative indicator for search rankings.
Former colleagues at Microsoft pointed out that they had a similar patent for using email as a method for detecting infected websites and removing them from search to prevent the spread of malware. In their view it seemed very likely Google was doing something similar, as "all the search providers buy data from Spam prevention services for helping to remove malware from search". Microsoft has a patent on this too. This isn’t a smoking gun, that Google does the same. The two search engines compete a lot, but they don’t go tit for tat on every feature.
In all honesty, we would hope that Google and Microsoft did this at least on some scale. You don’t want to reward the guys sending you 300 "as seen on TV" spams a day for herbal viagra, or Ashley Madison. So domains that spam should be penalized. It is creepy that everyone is data mining your email, but that is how email spam detection works in the first place, so if you are going to read my email to save me from spam in my inbox, why not also save me from spam in search results?
The infuriating part of all of this is the lack of transparency. I get that when you are judging an ice skating competition you don’t have to reveal why you gave the skater a 4 and another judge awarded a 5.5. But if Google can’t tell you the things you can get a penalty for, then there are issues. Even the Ice Skating judges will tell you what you get negatives for, it’s all the positives they don’t fully disclose. Same with credit scores and wine tastings.