Should an email client have a philosophy? I think so. For many people,
email is our primary means of communication. Something so important
ought to warrant a little thought.

So here's Sup's philosophy.

Using "traditional" email clients today is increasingly problematic.
Anyone who's on a high-traffic mailing list knows this.  My ruby-talk
folder is 350 megs and Mutt sits there for 60 seconds while it opens
it. Keeping up with the all the new traffic is painful, even with
Mutt's excellent threading features, simply because there's so much of
it---a single thread can span several pages, and God help you if you
lag behind. And Mutt is probably the best email client out there in
terms of threading and mailing list support.

The principle problem with traditional clients is that they place a
high mental cost on the user for each incoming email, by forcing them
to ask:
 - Should I keep this email, or delete it?
 - If I keep it, where should I file it?

For example, I've spent the last 10 years of my life laboriously
hand-filing every email message I received and feeling a mild sense of
panic every time an email was both "from Mom" and "about school". The
massive amounts of email that many people receive, and the cheap cost
of storage, have made these questions both more costly and less useful
to answer.

As a long-time Mutt user, when I watched people use GMail, I saw them
use email differently from how I had ever used it. I saw that making
certain operations quantitatively easier (namely, search) resulted in
a qualitative difference in usage. And I saw that thread-centrism had
many advantages over message-centrism, especially when volume was high.

So, in many ways, I believe GMail has taken the right approach to
handle both of the factors above, and much of the inspiration for Sup
was based on GMail. Ultimately, GMail wasn't right for me, which is
why the idea for Sup was born.

Sup is based on the following principles, which I more or less stole
directly from GMail:

- An immediately accessible and fast search capability over the
  entire email archive eliminates most of the need for folders,
  and eliminates the necessity of having to ever delete email.

- Labels eliminate the remaining need for folders.

- A thread-centric approach to the UI is much more in line with how
  people operate than dealing with individual messages is. A message
  and its content deserve the same treatment in the vast majority
  of cases.

Sup is also based on many ideas from mutt and Emacs and vi, having to
do with the fantastic productivity of a console- and keyboard-based
application, the usefulness of multiple buffers, the necessity of
handling multiple email accounts, etc.