Re: nnimap and crossposting (Re: Moving from nnml to nnimap...)

[Simon Josefsson <jas@extundo.com>]

Ken Raeburn <raeburn@raeburn.org> writes:

> Good idea ... except that one of my group names is constructed when
> the init file is loaded, using (format-time-string "all.%Y-%m").  And
> if I get to use Sieve eventually, the spam rating calculation, at
> least, would be likely to differ between Gnus and Sieve.

I use the same, although most of my split rules are already moved into
Sieve.  So the idea doesn't work well in these cases.

>> When nnimap crosspost split an article into several groups, it add
>> client-specific message flags on each message, indicating the mailbox
>> and article number of the other crossposted copies.  For example, if
>> article 4711 in mailbox INBOX.foo have a mark
>> gnus-crosspost-INBOX.bar-42, then when marking INBOX.foo:4711 the same
>> mark be applied to INBOX.bar:42 as well.  There is one immediate
>
> I'm told some IMAP servers like Cyrus will limit the number of flags
> to something like 32 per mailbox.  Even listing the group names and
> not the message numbers would quickly exceed that limit.  A single
> flag, gnus-(not-)crossposted, might be enough to tell Gnus whether or
> not the other groups need to be scanned, but it would still suck to
> have to rescan all of them.
>
> Too bad IMAP doesn't allow arbitrary client-defined string attributes
> for messages...

Well, IMAP does; the client-specific message flags are just that.  If
servers cannot handle many client-specific flags, then we can't use
this idea, though.  OTOH, it looks difficult to find any other
portable solution, so perhaps we can fix the arbitrary limit in Cyrus
and use this idea anyway.  Otherwise I think we're left with
client-instance-specific solutions like the nnmail message-id cache
backlog, which I agree are no good.

Even increasing the arbitrary limit from 32 to, say, 512, would
suffice for most people, I think.  For each specific mailbox, you
won't crosspost to that many other mailboxes, will you?  Hm.  Except
if you crosspost between a personal mailbox and list mailboxes, then
the personal mailbox will likely have crosspost flags to almost all
other mailboxes, eventually.

Perhaps bring this up with the Cyrus folks?