A better email client

The problem of email overload might be impossible to solve. I want to present a design for an alternative email client that needs evaluation beyond my disciplines. I don't propose this is 'the winner', but it's definitely an interesting route and I would appreciate your assessment.

Have a look at my mockup (screenshot here) and then read my thoughts behind these decisions:

1. Outgoing mail only utilises the subject line and attachments. The body is not available.
Email communication contains so much verbose etiquette (Dear Sam, How are you, Regards) which we have no capacity for in SMS or Twitter. To ignore this etiquette is rude. To write blatant subject lines is rude. I believe if a third party (a new email client) were to introduce a formal constraint (such as only using the subject line), it becomes socially more acceptable to skip the formalities of email. Subject lines have some character limit (sending 1000 characters would be ok) but one is naturally inclined to keep them brief.

2. Incoming mail is complete. The body is visible.
It is obviously important that users can read the body of incoming email. This is provided, but the response to incoming mail could only use the subject line.

3. Conversations are threaded by sender(s), not email threads.
Most people will be familiar with how iOS manages SMS threads, and how Facebook now manages message threads. These email threads would be grouped by people involved, not by traditional email threads.

4. Attachments are allowed
Required and not very problematic.

5. This would be a client to gmail.
This client would be a minimal client for gmail—which does an excellent job of providing tools to filter and manage emails. This manages email volume, very well. However, the persistent problem is how long it takes to read and respond to emails.

6. This is not displacing Twitter, Facebook walls or IM.
These mediums all exist alongside email. This is just a lightweight form of email, which is designed for a subset of email users (many of the power users) to use.

7. Known issues
- Gmail doesn't appear to manage threads by message-ID, but instead by some clever parsing of subject lines. That will need addressing so this system doesn't break non-users' inboxes.

Discussion
So far, this design has evoked some odd emotions from people I know—a mixture of curiosity, hate, and bafflement. I'm a product person, and I find it difficult to clearly understand the issues this product might introduce. I know nothing about IMAP libraries. I write Javascript and design interfaces, so I'm curious to hear a critique from the broader community.

Thanks for your time.

The irony is not lost on me that I'm emailing this blog post to Posterous.