Do you have zero or 10K+ messages in your inbox? The data we use to build Hotmail

Do you have zero or 10K+ messages in your inbox? The data we use to build Hotmail

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Last year, we shared some data about the behavior patterns of people using email. We found that we could group them neatly into three types based on their behavior—Filers, Pilers, and Deleters (we previously used the term “Purgers” instead of “Deleters,” but decided on a nicer term). One of the comments on that blog post said, “I am VERY happy you guys look into this kind of behavior, it must certainly be important when designing future uses of the product,” which was a nice comment and also true—we have, indeed, used this data over the past several months to create many of our new features. We thought it would be fun to share a behind-the-scenes look at some of the features we’ve released based on that data.

First of all, the most important lesson we’ve learned over the years is that people manage their email differently. Everyone has a slightly different way of approaching email, and it’s always interesting to see how people organize their inbox. Like you, I’ve sat next to someone in a meeting or on a plane and stolen a quick glance at their inbox. And like you, I’ve seen all kinds of crazy things: I have been shocked to see very organized people with 17,000 messages, and I am jealous every time I see a tidy inbox with zero messages. Some people are unabashed Pilers and others are proud Deleters. As we continue to improve Hotmail, we try to build a myriad of tools and tricks to help all kinds of users organize their inbox.

We found that most people are Deleters (53% of those studied). As the name implies, Deleters generally delete email after it arrives. Deleters receive an average of 211 email messages each week and end up deleting almost 80% of them. When we talked to these users, we found that they typically skim their inbox, delete everything unnecessary, and then begin to respond to the most important messages. The mantra for these people is, “My kitchen has to be clean before I start cooking.” In fact, they delete three out of ten emails (31%) without even reading them. Because Deleters want their inbox clean and tidy, their feature requests normally involve more tools for quickly cleaning out their inbox so they can get down to business. Sweep, for example, was a feature we built to make life easier for this type of users. Our goal is that Deleters can get to their most important email even faster after sweeping away anything they don’t want to read immediately.

Filers, on the other hand, are characterized by their zeal to move messages into folders. Filers make up a quarter of our users and receive slightly less email each week—201 messages—than Deleters. But Filers put nearly half of their email (44%) into folders immediately after it arrives. They are more likely to use our full range of features; a third of this group use vacation replies (32%) and almost half of them use keyboard shortcuts (44%). Not surprisingly, 53% of Filers set up custom filters or rules to route email to folders or subfolders. Filers often request advanced tools for routing and categorizing email. Because they value an organized inbox, we also assume that Filers often segregate their email even further and have multiple inboxes for different purposes. Multiple inboxes, of course, create inefficiency. This is especially true for Filers, since they have to maintain multiple sets of inbox rules. Our team looked at the problem from another angle and created the Aliasing feature. An Alias allows Filers to create several email addresses from a single Hotmail account. Because we had Filers in mind when we built Aliasing, we ensured that email sent to an alias could automatically be routed directly to a particular folder.

Finally, there are Pilers. These are the folks I mentioned earlier that have 17,000 messages in their inbox. Of the three types of users, Pilers receive the least amount of email each week (174 messages). But that means they still receive an average of 9,048 email messages per year. Because most of those messages (57%) never leave the Piler’s inbox, their email starts to pile up. By definition, the Piler isn’t excited about nifty tools for filing or deleting. Pilers want to keep all their email, so they need plenty of storage. But we did find that Pilers felt they “lost” email (read: were unable to find email) about 30% of the time and they also want to be able to find things fast. So we built a few of our recent features, like Advanced Search, Quick Views and One-Click Filters, with this type of users in mind. Even if Pilers don’t do anything proactive to sort or file their email, they can use Quick View and One-Click Filters to see all emails from Facebook, all emails with photos attachments, etc.

We have gotten several questions about the customer data to build Hotmail, so we put a bunch of the data and videos of the resulting features on a website. Take a look and let us know what you think.

David Law – Director, Hotmail Product Management


14 Comments
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  • I file away everything. Personal emails go in one folder, newsletters in another- account info in one and support emails in another.

    Unless it comes down to Twitter notifications, which I'll read the subject of, mark them as read, then sweep them away into the garbage. ^_^

  • im near solving but need help finalizing  in creating an app for safemode called livesecure mail

  • nektar
    8 Posts

    Your analysis is great. I am surprised that you plan new features based on such a scientific method. However, my problem is with the features themselves. The background analysis and work you did is excellent but the corresponding features are either bad or half-measures. Sweep for example is so as powerful as Gmail's Mute or Outlook's Ignore Conversation. As a feature it is also risky to accidentally delete e-mails from a sender and then discover that you needed to delete everything except say one of them. In other words it is inflexible. Also, the UI is bad:as it says "Delete All From ...". Delete all what? Emails it should say. And why ...? You know the recipient's name show it.

    For Quick Views and Filters, I still can't tell the difference between them. Why do you have both Quick Views and Quick Filters? Why two places from where I can filter e-mails?

    As you see the features are not designed very well.

  • Nice post!

    I have to say I am a piler :). I want to keep all my e-mails in my inbox

  • winter
    15 Posts

    Yes, it's essential to save a copy of chat text when using Messenger in hotmail. Hotmail has improved greatly, especially since last year. I am moving away from gmail. Thanks for your great work.

  • David Law
    11 Posts

    Thanks for sharing your inbox styles.  I’m a filer – I try to get my inbox as close to zero messages by moving as many as I can to folders.  Some days I am successful, some days I am not.

    @w1ngut  – thanks for the feedback.  Good feature suggestions for us.  

    @technackblogs, @abm and others on message history – good suggestions, too (and glad to hear you are using web chat/messenger in your inbox!).  We’ve heard this one from several users.  Nothing to report, but as always, stay tuned to this blog for any updates.

    @abm – great suggestion for Outlook-like attachments of emails.  That’s one I use constantly in Outlook and would use in Hotmail.

  • Completely agree with @techknackblog : "why don't Hotmail stores the chat history of Facebook and WLM?"

    This is a very important feature but dont know why hotmail has always ovelooked it. Not only hotmail even WLM does not online archiving feature (the feature it has now is of no use as it has no privacy as anyone can see your chat history if saved on a PC).

    I am a Piler cum Filer depends on the type of message.

  • abm
    268 Posts

    +1 @[storing the chat history of WLM and FB on Hotmail]

    Another suggestion -- no major web-based mail service has implemented it yet -- In Outlook we can attach multiple old emails by drag-drop the email in compose. In Hotmail we need to copy paste the text and it’s a nightmare if we need to attach multiple emails. Please provide another attachment category (besides Bing, images and office document) Attach Emails, and let the user select the existing email.

    Also, form Hotmail compose, please provide the mean to directly use the Office360 document from SkyDrive as an attachment.

  • I am a piler...too lazy to move everything lol

  • i'm piler favorites/rss-wise after a while i just got tierd of going thru old links

  • Hemingray
    85 Posts

    If it means anything, I don't even have a hotmail inbox. o.o

  • w1ngnut
    25 Posts

    I'm a filer that has more than 50 folders. Wonder if Hotmail team will help me with better folder features such as right-clicking and allowing me to mark a folder ready, empty my trash bin or collapsing / expanding them. Apart from that, extremely happy for using HM as my default mail.

  • Also why don't Hotmail stores the chat history of Facebook and Windows messenger??

  • I am Filers....but I am lazy to delete the mail which are pending....and which are of no use to read...