On 11.4.2013, at 1.40, SM <sm(_at_)resistor(_dot_)net> wrote:
Hi Timo,
At 14:22 10-04-2013, Timo Sirainen wrote:
GMail's submission server saves all the submitted mails to the sender's Sent
mailbox. After this most IMAP clients with their default configuration will
again save the same mail to the Sent mailbox. I'm not sure if GMail removes
one of them as a duplicate or
I assume that you have read Gmail's answer about the handling of the /Sent
mailbox.
Not really. I've seen some random mails that GMail doesn't do any duplicate
prevention, but somehow I thought it there would be something.. at least in
theory there could be.
not. I've been considering doing a similar feature to Dovecot (it will most
likely have a proxying submission server in near future), but it would be
nice to tell the SMTP clients that this auto-saving is happening, so they
could skip the IMAP APPEND part with default configuration.
Of course there are the LEMONADE extensions that are supposed to solve this
same issue, and Dovecot will support those as well, but I think it's going
to take a while for clients to actually implement those. There's likely much
better chance of them implementing a small check for "oh, the mail was
already saved, I'll just skip the IMAP APPEND." Even if any clients
themselves didn't implement this, it would make it possible to implement a
simple SMTP+IMAP proxy locally that catches the flag and supresses the
APPEND before it reaches the network.
So, any thoughts on creating an RFC for this functionality? I'm not familiar
enough with SMTP yet to know what would be the best design for that
notification. Maybe a new extended status code? Maybe change some of the
DATA reply's text part to have a special meaning? A simple flag is enough I
think, because it's reasonable to require that both the server and client
supports IMAP SPECIAL-USE to find the \Sent flagged mailbox. Returning IMAP
UIDVALIDITY+UID could help IMAP clients a bit more, but that's maybe a bit
too ugly (and not always possible).
In the above you have the SMTP (MSA) client and the IMAP client which are
acting independently. If the mail client already knows that the message has
been saved to the Sent mailbox it could use the
Message Submission BURL Extension to submit the message to avoid the
"duplicate submission".
Suppressing the APPEND may be problematic. The MSA server can reject the
submission attempt with a message mentioning the IMAP mailbox automatically
used to submit the message. BTW, what you are looking for might be what
behavior the mail client should set at configuration time to provide mail
functionality. This means detecting the features offered on the server side.
My understanding is that most email clients first send the message to
submission server, and only after that is successful they are saved to Sent
mailbox via IMAP APPEND. My whole auto-save-flag idea relies on that..
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