Every single day, people send about 294 billion emails and the average knowledge worker now spends close to 13 hours per week on managing email. Over the last few months, we have seen a number of tools that help users to manage their email in Google's Gmail more effectively. Today, Google itself is joining the fray with Priority Inbox. Once activated, Priority Inbox splits your Gmail inbox into three sections: important messages, starred messages and everything else. The system automatically learns which messages are most likely to be important to you and places them at the top of your email queue.

As Matt Glotzbach, Google's product management director for Google Enterprise, told us earlier today, Priority Inbox functions like a reverse spam filter. Instead of looking for spam, however, Priority Inbox tries to determine which emails are most important to you. It examines a number of implicit and explicit signals, including who the people are that you tend to email most often and which emails you star, delete, archive and answer. You can also train the algorithm explicitly with the help of a +/- button. Based on this algorithm, Google then calculates a priority score for every email and will push the most important messages to the top of the list.

Until now, most of us just organized our inbox chronologically. By focusing on "importance," Priority Inbox uses a very different paradigm. According to Google's own data based on early tests of the system, "testers spent 6% less time managing email after enabling Priority Inbox." While that does not sound like much, it adds up to a whole week of recovered time each year for the typical information worker.

In addition to the focus on important messages, Priority Inbox also adds a new section for starred emails to your inbox. If you use Gmail stars regularly to mark messages that you need to act upon at a later point, you can now rest assured that these starred messages will remain visible in your inbox and won't get pushed to the next page and out of sight by new mail.

Customize Your Priority Inbox

Google allows users to extensively customize Priority Inbox. You can change how many messages you see per section, for example, and you can also choose which sections you want to see in your inbox (Important, Important and Unread, Unread, Starred, etc.). Of course, you can also choose to turn Priority Inbox off. These customization option are available through the Gmail settings menu and also directly in the Gmail interface.

Getting Things Done with Priority Inbox

Earlier today, we also got a chance to talk to David Allen, author of Getting Things Done, about today's new Gmail features. Allen, who is well known in technology circles for his ideas about productivity and managing email, told us that he was rather skeptical when he first heard about this new tool. After talking to Google about it though, he now thinks that it can help Gmail users make more effective decisions about their email and to avoid constantly looking at their email in what he calls the "emergency scanning mode" because they have no way to prioritize all the messages in their inboxes. Allen also thinks that the combination of Gmail stars in addition to the algorithm will help people to remain in control of their email. The assumption behind this, of course, is that Google's algorithm does indeed work as advertised.

In our own test this afternoon, the algorithm did a good job at highlighting important messages, but we will have to test it over a longer period of time before we can make a definitive statement about its usefulness.

Availability

Google plans to roll out Priority Inbox to all regular Gmail accounts and Google Apps users over the next day. For Google Apps users, the account administrator has to flip "enable pre-release features" switch in the Google Apps settings before users can access this new functionality.