Filters [Was [ANNOUNCE] Filters patch

[Emmanuel <e allaud wanadoo fr>]

	Hi all,
just to sum up how I see filters for now and how they should evolve (the
thread was so long that I think this is necessary, at least for me).

First I think the real need for built-in filters in Balsa is to filter
mailboxes to find messages meeting certain criteria (typically when you
have huge mailboxes, it's now almost imposible to find a precise message or
even a thread).

And if you have coded filters for that purpose, it is not so much work to
have them filter on incoming mails (pop3 is OK for now, I don't know how to
do it for others, eg this seems impossible for local mailboxes). Obviously
this is not a replacement of procmail, it's an alternative. We can even
export balsa filters as a procmailrc file if this seems useful.

About sieve format : I think for now that we can export built-in filters to
sieve, and even store built-in filters in sieve format. But I think that
this should be done only if we want that balsa built-in filters can be used
for delivery (ie in a MTA-MDA fashion). Indeed sieve is a bit over-design
for "message lookup" filters, IMHO.

Opinions?