The Android GMail client is a perfect example of what a client looks like in this world. It talks to the (secret / private) GMail API, it does offline mail reading, and queues actions so you can archive / filter / whatever mails while offline and it’ll push changes later. You can read and write mail. It doesn’t try to do anything clever, because anything clever done on one client isn’t reproduced on any other client. And if I don’t have a client on my current computer for GMail, I can use a web browser, and still get all the features of the server. I use the web gmail interface for everything anyway, because it’s better than any GUI client I’ve got.

I dont know - this guy makes for pretty convincing arguments on why email should be done right on the server rather than the client. Which effectively means a new protocol.

(For example, I don't like gmail's flat "conversation" view; I much prefer a "threaded conversation" view, like classic Usenet readers, or HN discussions.)

I think what is meant by a new protocol and server innovation is a change in the data model. I do not believe they are going to dictate views.

Yes, we could be happy with the status quo. But I do believe that one of the things that's holding up innovation around email is the lack of easy access to data. Proposed exercise: Write a script that downloads and displays your Twitter feed. Then write a script that downloads and displays your email. The email exercise will take you an order of magnitude longer.

Spam filtering isn't the problem you make it out to be. I get more spam in my Facebook inbox (mostly viruses) than in Gmail. If you're hosting you're own email or are using a sucky provider, that's a different story.

Email will be hard to replace long-term anyway. I doubt your bigcorp employer really going to let you send work-related Facebook messages. IM is a fundamentally different protocol with different use cases (think async vs. sync, fax vs. phone).

  $mbox = imap_open( $host, $login, $password );
  foreach( imap_search( $mbox, 'UNSEEN', SE_UID ) as $uid  ) {
    $header = imap_fetch_overview( $mbox, $uid, FT_UID );
    echo $header[0]->subject . "\n";
  }
  imap_close( $mbox );

    $status_url = 'http://twitter.com/statuses/user_timeline.json?screen_name='.$user;
    $timeline = json_decode(file_get_contents($status_url));
    for($i = 0; $i < count($timeline); $i++){
        echo $timeline[$i]->text ."\n";
    }

IMAP and MIME are hard because there is a higher level of information that is available. Can you attach an archive over Twitter (not link to but attach)? Can you send HTML? They are not the same thing. If you want something really simple your code will be simple. If you want more use cases than "i can haz cheeseburger" then you need more expressive power and more complexity.

As is believing that it's about spam (or probably believing it all, for that matter, but let's stay on topic).

I don't understand people bitching about spam in 2010. I have probably a dozen email addresses that I publish all over the web and I get maybe one spam message a month. I get way more "spam" through Twitter than I do through my email.

I have had false positives with every single spam filter I have tried. This is unacceptable when running a business, and if we manually have to double-check hundreds of spams each day, what is the point of the filter?

Additionally we spend hours each week working with users who do not receive our emails because of spam filters unknown to them (many believe the fault is ours).

It is 2010 and spam is still a major problem.

It's faster to scan a list of subject lines and senders than to look at the contents of an email, which is faster than actually deleting it. So verifying that the spam filter sorted your emails correctly is faster than sorting every message yourself.

A better protocol will only be "better", analogous to, say, the Mac (c. 1990) being better than Windows 3.1. While true, compatibility pressures aren't going to allow someone else into the market simply for being "better". You have to be transformative, and this isn't.

And in any case what's killing email isn't the lack of apps, it's the lack of authentication and moderation.