Google’s Priority Mailbox and the Future of the Web


A few days ago, a PDF showing how Google’s Priority Inbox feature works circulated among the Hacker News and email marketing communities. The paper shows how the future of the web is evolving to deliver hyper-personalized results to users while relying on a huge sample of people connected through the cloud.

Priority Inbox, which attempts to deliver the most relevant emails to the top of a user’s inbox screen, combines the behaviors of all Gmail users with your personal preferences and behaviors to deliver an inbox where your most important mail gets read first.

It’s as if your doctor could compare your physical complaints with all of the symptoms experienced by people everywhere in the world, in order to deliver a diagnosis in a few seconds. Not impressive if you have a cold, but if you suffer from a rare disorder, it’s amazing. The paper is chock full of math and explanations of how Google (s goog) does this at scale (sharding databases and using Bigtable across tens of thousands of servers), but the crux of the matter is Google trying to apply machine learning to determine what each Priority Inbox user cares most about. To do that requires a computer connected to the cloud, and Google’s back-end servers. It’s an illustration of how massive computing power in the cloud and a client device can interact in ways that benefit users.

The biggest challenge isn’t necessarily the huge data crunching on the back end; it’s accounting for what the paper’s authors and statisticians call “noise,” and what I call the oh-so-human tendency to do what we want, not what’s most productive. For example, in email, we waste a lot of time and productivity opening silly emails about Lindsay Lohan’s latest escapades while ignoring those from our boss:

Opening a mail is a strong signal of importance for our metric, but many users open a lot of mail that is “interesting” rather than “important”. Also, unlike spam classification, users do not agree on the cost of a false positive versus a false negative. Our experience showed a huge variation between user preferences for volume of important mail, which can not be correlated with their actions.”

The challenge for machine learning is to calculate the signal from the noise on a massive scale in real-time, so your LiLo emails get sent to the bottom of the stack, but can still be read.

The researchers say that for Googlers who receive similar volumes of mail, Priority Inbox users spend 6 percent less time reading mail overall, and 13 percent less time reading unimportant mail. So while Priority Inbox may end up making you more productive, you might have less to chat about at the virtual water cooler. Unless you use those time savings to hang out on Twitter.

Do you use Priority Inbox? Do you think it makes you more productive?

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Jeff Yablon

My concern is that “users can always opt out” (or statements like that) don’t take into account that the reality that as a whole users don’t “get it”. So they’ll think that Google is giving them what they want, while in reality a lot of stuff will just vanish.

The goal may be admirable, but the results are terrible.


I must say it is a pretty sleek ‘NEXT’ feature in Gmail. This was the only logical step they could take considering the amount emails, going in and out. It would be effective ONLY IF, the learning algorithm, ACTUALLY take in account what Gmail users tag as “important” or “not important”.

Michael Martine

Priority inbox is a great way to completely fuck up your life. You will miss things that are important and it will fail to obey you when you mark something as unimportant and continue to list subsequent emails as important.

Turned it off after a good month of giving it a solid try.


You’re not ceding anything to Google. Priority Inbox brings “important” emails to the top, but the rest are still there.


There’s no algorithm, Jeff. Google doesn’t control what’s important or not. It’s controlled by the user who marks conversations as important or not.

Jeff Yablon

Yeah, I understand that as a concept, and from playing around with the feature I agree that the user has some control. But there’s clearly a bunch of “Crunching” going on in the background (as noted in this piece), and given that *most* people won’t have the time or inclination to figure out how to override it, I think being afraid of this makes sense . . . !

Stacey Higginbotham

Also, a user can decide whether or not to use Priority Inbox or not. So if you are worried about ceding control, you don’t use it. But technically the challenge that Google is dealing with is massive and complex, so papers such as this are enlightening.


Wait, do I get that right. First one creates a massive system, then when one has to deal with it it’s smart. You know there is nothing in the email RFC that says the system has to be centralized.

There is also nothing is any RFC that email has to be in one large inbox. In the 80/90’s we had a system called procmail, developed at Uni Aachen Germany, which could put mail for example into projects. So all Documents would be together, design, email about design …

Today one would expect to have autonomous context organization and not one big data silo with points to nowhere, nice overview though. But from a productive point of view rather pathetic.

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