What I’m thinking of is a mode in email clients that would show you 4-8 small message areas that you could browse. One button would let you trash them all, or apply a label to all of them, or perform some other group/bulk action.

It’s not the actual filtering I’m that concerned about – whether X-header are used or something else or whatever (though I agree it seems a ‘natural’ choice given the history of email and processing thus far). The bigger concern is how to come up with those labels/tags/whatever to stick in the X-headers in the first place. Given the disparity of email systems out there, and the disparity of address book formats (and I’m also thinking about the feeds idea and such) it’s a daunting task.

We definitely have plans for non-Outlook users, but we’ve found that the level of pain is the highest in traditional business email users – which more often than not means Outlook and Exchange, so that’s where we’ve started.

The bigger and more complete solution we envision is one that lives at a higher level than any individual messaging system/platform. Once you’re using the same system across multiple messaging systems, then even if you’re no longer using something like a corporate Exchange system, other systems you use (Twitter, AIM, GMail, etc.) will already know about the level of importance those contacts have. So, abstracting these concepts to a higher level across multiple messaging systems definitely is something that would help with portability.

The only drawback I can think of is that for many people there’s still a learning curve for the system to learn each person’s histories. Well, I guess not, to the extent that the ’sent’ messages could be used. Tracking interaction history across multiple systems would prove tricky – if I change companies, my history of dealing with ‘bob’ is lost when I move to a new company, for example. At least it would if you’re focusing on corporate mail systems. Coming up with a way to address the person/individual market and make this portable would be fantastic.

My company has been focused on this for a while. Check out my response to TechCrunch at http://www.emaildashboard.com.

“The filter would consult your address book and analyze your behaviour with that person before. … Your email program would then allow you to construct views based on those labels.”

That’s basically what our ClearContext IMS product does with inbox views already for Outlook users – more platforms definitely on the way.

“However, I’m envisioning taking that a step further, as most email systems have a rather limited view of your ‘address book’.”

Your ideas re: other inputs to help identify the nature and importance of email are very valid. And if you extend it a level, you can make it a two-way thing. What do I mean? Well, as you say, if someone’s email address is related to a corporate blog, then most likely the communication has something to do with that company. On the reverse side, if I get a Facebook feed or Twitter or other online communication, by looking at my email history, the site/app can see how important that person is to me and highlight the message accordingly.

As our interactions with overlapping groups of contacts span more and more types of communication, there are more and more contextual clues available to us to help identify and process them in a more intelligent and efficient way. And with the increasing volume of communication, that’s not a nice thing, it’s a requirement.