[Dovecot] Server-side sieve for client-side copies

[Daniel L. Miller]

Eduardo M KALINOWSKI wrote:
> Daniel L. Miller escreveu:
>> So, without changing the MUA/MTA/IMAP interaction, the IMAP server 
>> will simply file new messages according to user-set rules.  Doesn't 
>> address the multiple-transfer issue at all, but does provide an 
>> option for centralized control of message filing.
>
> With the APPEND command, storing the mail somewhere that is not the 
> default location would be a violation of the protocol:
>
> 6.3.11. APPEND Command
>
>   Arguments:  mailbox name
>               OPTIONAL flag parenthesized list
>               OPTIONAL date/time string
>               message literal
>
>   Responses:  no specific responses for this command
>
>   Result:     OK - append completed
>               NO - append error: can't append to that mailbox, error
>                    in flags or date/time or message text
>               BAD - command unknown or arguments invalid
>
>      The APPEND command appends the literal argument as a new message
>      to the end of the specified destination mailbox.  This argument
>      SHOULD be in the format of an [RFC-2822 
> <http://www.faqs.org/rfcs/rfc2822.html>] message.
>
>
> The simplest solution would be, as already mentioned, configure the 
> client to BCC yourself, and filter that message. (And disable the 
> 'Store copy of sent mails' option.) I do not think running filters for 
> APPEND'ed messages is an option (even if one not active by default).
First - I can't argue the point about BCC'ing - you're certainly correct 
that that would be the "simplest" solution in terms of immediate 
implementation - if we assume users are willing to change their habits.  
Since I don't - I'm exploring server-side options

I disagree about "violating" the protocol.  Nothing about the mail 
server/client communication would change - the client would still 
receive an "OK" at the end.  The difference would be after the message 
appeared in the "Sent" folder (or never show at all), a moment later it 
would disappear and be placed in the sieve-directed folder.  I don't see 
how this violates the protocol - though I do agree it would be quite 
confusing for someone who wasn't aware of this behavior.
-- 
Daniel