Email today has many annoyances. Even though we now seem to have a grip on the spam problem, many users are suffering from email overload: There are just too many emails flooding the inbox. Many are drowning in heaps of emails that aren't even important – it's just a colleague at work Cc-ing everyone evenly remotely connected to his project.
There are plenty of ideas on how to improve the current state of mail clients, and I'll present some of them here. None of this is my work: I'll give references to publications of others. There are literally hundreds of papers on this subject, so I've chosen to present my selection of personal favorites.
Here are the three ideas I'll present:
Task-Driven E-Mail OrganizationPeople's lives today are organized in their mail client. It's not just communication that takes place here: Meetings are organized, lists of todos and deadlines are exchanged, documents are sent around.
In effect, what you're keeping track of in your email client are tasks. Most emails you get are part of some project, belong to an event you're attending or organizing, or are part of a greater plan, e.g. keeping in touch with a girl.
That's the idea behind TaskMaster , a tool developed at PARC in 2003. All your emails, drafts, attachments, and bookmarks are mapped to "thrasks". Emails in the same thread are grouped automatically, but the user still has to assign other mails, links, and deadlines manually.
Thrasks can have associated actions, such as "call this person", and "review this". You can also add deadlines to each task: they are shown as green and red bars as they approach. Documents can be previewed right inside TaskMaster's UI, as seen with the Word document on the bottom.
I think the great advantage of this approach is that items that belong together are displayed together. Instead of using email folders to hold related messages, the central element is the task, with all the associated deadlines, todo items, and documents.
Here's a quip from the paper's usability interviews:
"It's just nice to be able to have the control over mixing [...] related things together, even though they might not be [...] the identical kind of thing."
What if we went a step further and looked at workflow patterns? For example, at a company where you interview candidates in a formal hiring process, you get automatically generated messages reminding you of the interview, requesting feedback after the interview, and a notification of the final decision. In the future, we might be able to automatically identify the structure of such processes  and classify email into these activities  – both of which goes beyond Taskmaster's model, which requires some manual effort.
Creating Smart Organization StructuresAlmost everyone I know keeps incoming email entirely in the Inbox. Newly arriving messages join the 500 messages already marked as unread and are displayed at the top of the pile. Is there a better way to organize this view? Can we sensibly restructure incoming mail?
Bifrost , a plug-in originally conceived at Lotus Research, that takes this approach. The idea here is that the people are the main indicators of whether an email is important. After installing Bifrost, you're asked to sort your contacts into five groups: Your own email addresses, "VIP Platinum" (extremely important people, e.g. your manager), "VIP Gold" (important people: friends and family), as well as small and large distribution mailing lists.
Bifrost then reorganizes your inbox and displays your email in a number of predefined categories:
- Timely: Emails that contain today's or tomorrow's date in the subject line. They'll likely be important today, but not next week.
- VIP Platinum: emails from your manager.
- VIP Gold: emails from friends and family.
- Personal: replies to emails you've sent out, emails sent directly and only to you, and any unclassified emails you receive.
- Small distribution: Intended for group messages.
- Large distribution: Large-distribution mailing lists.
This structure is helpful in identifying important messages and weeding out the less interesting ones. A quote from their user interviews:
"If I am running through an inbox, I might be tempted to read a title and get sucked in because it is interesting. Whereas if it is in a pile of listserv stuff, I just ignore it altogether. That was a nice thing when I was busy, to not get distracted by unimportant mail."
It's interesting to note that except for differentiating small and large distribution messages, this approach can already be replicated in today's email clients. You can simply create search folders or message filtering rules which simulate the Bifrost behavior. However, this would put emails into folders and wouldn't offer the one-page overview that Bifrost has.
Cool New FeaturesReMail  was a project at IBM Research that ran from 2001 through 2004. It was basically a reimplementation of an email client from the ground up and had several cool new features. I'll describe two of my favorites below.
Thread Arcs visualize relationships between email messages. Instead of wasting lots of space with a tree view that Thunderbird has, it displays the thread structure in a little image. This feature helps you see where you are in a long conversation. For example, in the picture below, emails B, C, D, E, F, and H are all direct replies to A, while email G is a reply to E.
The advantage of thread arcs is that you can see the position of the email you're viewing in the larger conversation, without having to switch to a tree view: your main inbox pane remains sorted by arrival time.
Contact Maps offer a different view of the address book: Senders from which you have received email are grouped by domain. Each person's name is shown with a different background color, depending on the time of the last email exchange. This offers a better view of your contacts than the traditional non-grouped lists where your least important contact looks just like your most important one.
Many of ReMail's other ideas can be found in today's popular clients: Instant messaging is now integrated with Gmail, which also groups emails by thread. The collection mechanism in ReMail is semantically equivalent to Gmail's labels. Outlook integrates emails and calendaring and has list separators ('today', 'yesterday', 'last month'), just like the ReMail prototype.
ConclusionsIt seems like the ideal email organization tool would be like your personal, smart secretary: It knows what's important or interesting, and deals with stuff you don't want to be bothered with. That would be perfect.
Today, we seem to be at a point where it seems like we might be able to solve the spam problem. But the problem of figuring out which of the non-spam emails is important, and what it relates to, still exists.
One solution – the one I presented here – is to add nifty features to the mail client. But would all these features really be understood and used? Users today seem to be using a very basic set of mail client functionality. Anything we add should not only solve a painful problem, but also be easy to use. I'm not even sure this applies to the applications I've shown here: You don't know until you've tried.
What do you think? Are these good ideas? Would normal people who are drowning in email use these features? What features can't you live without? Post a comment and let me know.
Thanks to Keno Albrecht, Bálint Miklós , Markus Egli, and Fabian Siegel for reviewing drafts of this.
ReferencesA more thorough and academic overview of the subject:
 Steve Whittaker, Victoria Bellotti, Jacek Gwizdka: Email in personal information management, Communications of the ACM, 2006
Examples of task- and activity-based systems:
 Victoria Bellotti, Nicolas Ducheneaut, Mark Howard, Ian Smith: Taking email to task., CHI, 2003
 Michael J. Muller, Werner Geyer, Beth Brownholtz, Eric Wilcox, David R. Millen: One-hundred days in an activity-centric collaboration environment based on shared objects, CHI, 2004
 Nicholas Kushmerick, Tessa Lau: Automated email activity management: an unsupervised learning approach, IUI 2005
 Mark Dredze, Tessa Lau, Nicholas Kushmerick: Automatically classifying emails into activities, IUI 2006
 Olle Bälter, L Sidner: Bifrost inbox organizer: giving users control over the inbox, NordiCHI, 2002
 ReMail: Reinventing Email Website, Collaborative User Experience, IBM Research, 2003