Re: New models for email (Re: e2e)

On Aug 21, 2007, at 4:59 PM, John C Klensin wrote:

> I'm not convinced that is worth it --and strongly suspect it is  
> not-- but, if Doug believes otherwise, I'm looking forward to  
> seeing a proposal.
I hope to have a draft ready in the near future.  When SMTP was  
developed, HTTP did not exist in its present state.  HTTP over a  
clustered file system is now able to function as a separate message  
channel for even the largest provider.  This separate channel can  
significantly lower the +90% levels of spam currently carried by  
SMTP, while also substantially moving the burdens toward the sender  
where it belongs.
Why change?  When a sender is suspected of spamming, the receiving  
MTA could limit exchanges to Transfer By Reference instead of issuing  
an ultimately more expensive refusal or message acceptance.  In the  
case of TBR, SMTP would be limited to just exchanging an HTTP message  
reference within the SMTP envelope.  This separate HTTP channel  
provides both delivery confirmation, and ensures the validity of the  
reference.
Whether the message is accessed depends solely upon the reputation of  
the HTTP publisher.  Any additional information could be abused and  
might require filtering.  Filtering burdens the recipient, where bad  
actors enjoy a significant advantage.  Not  relying upon filtering,  
finding an identifier independent of the IP address, excluding  
"friendly" information, and reducing the burden on the recipient are  
the general guidelines.
As the message reaches the MDA, the MDA would have the option to  
proxy access via BURL, fetch the message and revert to a normal SMTP  
form, or convert the reference into a pseudo message compatible with  
MUAs where recipients decide whether a message is to be accessed.   
TBR does not prevent spam, however it significantly lowers the  
recipient's burden and provides a simple means for avoiding unwanted  
or spoofed messages.  Details will follow in a draft.
-Doug





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