I am of the opinion that IMAP is fundamentally flawed. I am not sure the compromises it makes (improved bandwidth usage for increased server computational burden, for example) are entirely successful. It seems like it would be better to have the primary benefit of IMAP (server-side mail storage) without the protocol overhead.

I would advocate using http for mail retrieval as a better alternative. If the server-side computations provided by imap are desirable they could be implemented as web server extensions.

I would additionally suggest that the server keep a log of all transactions for a given mailbox so that client states could be quickly synchronised without placing undue computational burden on the client.

There would have to be a standard for the webserver extensions mentioned above. And a standard way of making the client aware which are available. GET /extensions comes to mind for the latter.

SSL would most likely be a must, as would some authentication stronger than HTTP's BASIC.

Pros:

• Server-side mail storage
• Simple protocol
• No new protocols are introduced
• Server no longer has to parse the absurdly varied mails it will receive

Cons:

• Increased client-side computational burden (server no longer parses mail)
• More bandwidth usage (could be traded for computational burden with server extensions. Server-side searches are the most obvious of these trades.)
• Hell, some of our users still haven't switched to IMAP from POP3. Why would they switch to this?
• No clients yet except web browsers and that would be pretty unpleasant.
• Mail delivery agents would need to be changed (although in many cases the changes would be minimal or simple)

*shrugs* I'm just rambling.