Re: [imap5] Feature set? - was Re: Designing a new replacement protocol for IMAP

[Adrien de Croy <[e-mail]>]

On 17/02/2012 5:40 a.m., Tony Finch wrote:
> Adrien de Croy<[e-mail]>  wrote:
>>> With XSEND, you upload the message to IMAP first, then you say:
>>>
>>> TAG XSEND UID
>> how do you provide the SMTP forward path?  Is that scraped from the headers?
> That's the right thing to do. You also need to do BCC: processing.
> (sendmail -t does the right thing.)

I think the guys that developed SMTP would disagree with you.  The 
reason the envelope is even specified in SMTP rather than the receiver 
simply scraping them out of the message, is that sometimes you need to 
deliver a message somewhere other than the To: / bcc: headers.

> The rationale for BURL is that there is more to the SMTP envelope than
> just the sender and recipient addresses - in particular there are the DSN
> attributes. There's a somewhat ugly and ill-defined split between
> information for MTA processing (in the envelope) and information for MUA
> processing (in the headers - see MDN for example). But in fact MTAs do
> header processing too, so there no practical advantage to ESMTP envelope
> extensions and a lot of complexity disadvantage.
>
> There are a few envelope extensions: DSN, future release, message
> tracking, CONNEG and CONPERM facsimile media conversion, and 8BITMIME +
> BINARYMIME. If you want to eliminate BURL you need to either define a
> mapping from headers to the extension parameters that you want to support,
> or embed ESMTP inside IMAP.

yep, I'd definitely go for embedding SMTP into IMAP... since

a) SMTP is a trivially simple protocol for an IMAP server to use to 
submit a message on behalf, whereas an IMAP client is much more complicated,
b) take a look at the security implications in the BURL RFC.

Adrien

>
> Tony.

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