Re: [imapext] Three kinds of IMAP extensions

On 10/19/15 11:44 AM, arnt@gulbrandsen.priv.no wrote:
> The drafts folder does not count because nothing appended there is big
> enough to care about this extension.

Anything with photos or videos or other rich media/files in it runs the 
risk of being too large. Clients are increasingly doing incremental 
save-to-draft as users compose messages, so whatever the user composes 
ends up "in the cloud" within a few minutes.

>
> The other folders... suppose you are an iphone client, and you are to
> send mail, and it is big and you care about that. What do you do, upload
> twice, once to port 587 checking its limit and once to IMAP checking its
> limit? Or do you upload just to 587 and bcc yourself?

This is a different problem than what is being addressed by the draft, 
though I agree it's one that should be tackled by the group.

Somewhere in amongst SMTP BURL (rfc4468), IMAP Submit 
(https://www.ietf.org/archive/id/draft-kundrat-imap-submit-02.txt), and 
IMAP Catenate (rfc4469) seems to be some good concepts that will help 
address this other problem.

>
> This extension must be very simple to understand and implement if it is
> to be worthwhile against such questions. I have no idea whether even the
> simplest is simple enough.

For server dev, I'd think the simplest is to add 
"APPENDLIMIT=<your-servers-appendsize-limit>" where 
your-servers-appendsize-limit ideally comes from some existent limit 
configured in your server. This is what we implemented.

For client dev, I'd think the simplest is to look for "APPENDLIMIT=" 
capability and steer users away from trying to do operations that would 
require appending oversized messages -- "Your draft/note is too large to 
save" or "Sorry, that message is too large to copy from AccountA to 
AccountB. AccountB only accepts messages less than <appendlimit> bytes."

Perhaps I'm oversimplifying, though :)

>
> Arnt
>
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