[Dovecot] Pigeonhole sieve re-filter extension?

[Stephan Bosch]

T.B. schreef op 7-5-2014 10:40:
> I think it would not be a problem to develop a solution to remotely 
> trigger re-filtering for me, myself and I. But that is not the point 
> here. Clients like the Thunderbird Sieve Extension 
> (https://github.com/thsmi/sieve, 
> https://addons.mozilla.org/de/thunderbird/addon/sieve/) or the diverse 
> webmail MUA's will only start implementing such a feature if there is 
> a official draft or specification. 

Yes, I agree.

> The whole point of my initiative here is that Managesieve finally 
> becomes the capability to replicate the features the users know from 
> their local client side filtering (Thunderbird, Outlook) which provide 
> the feature of re-filtering. Even big webmail providers like the 
> Global Mail Exchange / GMX here in Germany provide re-filtering in 
> their webgui.

I don't think this should be a ManageSieve feature. ManageSieve 
currently does not need/have access to the user's mailbox. It therefore 
also doesn't have the syntax elements and mechanisms in place to select 
mailboxes and ranges of messages. I think the only sensible place for 
this feature is IMAP.

> I use the sieve-filter tool very often for myself - everytime when I 
> create a new subfolder and create a new fileinto rule, I refilter my 
> Inbox to clean it up and have a consistent subfolder with all old and 
> new mails that are matching the rule.
>
> The man page of the sieve-filter tool is 2 and a half years old ;) 
> (http://pigeonhole.dovecot.org/doc/man1/sieve-filter.1.html)
> Sadly even the Wiki page doesn't mention it directly: 
> http://wiki2.dovecot.org/HowTo/RefilterMail

I haven't received much feedback about this command line tool. So either 
everyone is happy with it, or it is rarely used. :)

> Since the new german Dovecot book (http://www.dovecot-buch.de/) 
> recommends the sieve-filter tool for refiltering, it will get much 
> more attention in the future.

Only from Germans at first, although it will be translated soon I guess.

Anyway, I will give this idea a closer look somewhat soon. The main 
problem with IMAPSieve is not the METADATA support or the other Sieve 
extensions needed for it, it is the atomic nature of the IMAP commands 
for which it is used: either the whole command succeeds or the whole 
command fails. This makes things difficult for the Sieve interpreter, as 
it needs to keep record of what it has done for when a rollback is 
needed. Especially for "redirect" this is a huge pain.

However, as you rightly say, this new feature can be simpler than that. 
It can reduce the atomicity to include only the processing of individual 
messages and e.g. return a response indicating which messages were 
successfully processed. This way, the state at client and server can 
still remain consistent without too much trouble. I think I'll make a 
proof-of-concept first and then condense my experience into a proper 
specification. This can take a while though; there is much Dovecot stuff 
on my list at the moment.

Regards,

Stephan.