Obviously email doesn't support seeing someone type, but SMTP is almost as fast as XMPP - sub 1 second doesn't really make a difference, it's usually IMAP that's the slow bit. Of course it's just as fast as XMPP if both sender and recipient are using post.fm, but the real latency comes from the recipient using eg gmail which has really slow IMAP polling in the web client (plus having to go back to the inbox or clicking show new message in gmail). Post.fm doesn't use IMAP under the hood so its instantaneous (and querying your mail in SQL lets us do amazing stuff).
its a new email platform to rival gmail, but we're stealth still so i cant disclose much. we'll be starting a beta pretty soon and issue an official press release at that stage - make sure you request an invite in the meantime.
