New mail in folders notification?

[Garry]

Hi all,

I have a (maybe stupid) question about Cyrus & new mail notification (or
whatever is responsible for it).

To start off, I've been running Courier IMAP on my mailserver for quite
a while, and usually got all my mails through inbox, with the MUA
(current Thunderbird 3) doing the mail sorting into several folders.

I thought it might be a good thing to have the server do the sorting for
me, as I want to use my Mobile phone for access (which doesn't have mail
filters of course) so I installed Cyrus on another box, everything
working fine so far. Setting up the Sieve filters wasn't much of a
problem, either, mails are correctly sorted into the folders as desired.

Anyway, I've now noticed that Thunderbird doesn't display the folders as
new with the number of mails in them ... at least not all of them ...
sometimes it will correctly show a new incoming mail, while other (most)
times, I need to go to the folder ...

Is this a basic problem/shortcoming of the MUA, or a configuration thing on Cyrus?
Having the folders and seeing new mail has come in is the point of doing
this to begin with ;)

Here's some info from my Cyrus install:

name       : Cyrus IMAPD
version    : v2.2.13-Debian-2.2.13-19 2006/12/19 19:32:59
vendor     : Project Cyrus
support-url: http://asg.web.cmu.edu/cyrus
os         : Linux
os-version : 2.6.18.8.xs5.0.0.10.439
environment: Built w/Cyrus SASL 2.1.23
             Running w/Cyrus SASL 2.1.23
             Built w/Berkeley DB 4.7.25: (May 15, 2008)
             Running w/Berkeley DB 4.7.25: (May 15, 2008)
             Built w/OpenSSL 0.9.8k 25 Mar 2009
             Running w/OpenSSL 0.9.8k 25 Mar 2009
             CMU Sieve 2.2
             TCP Wrappers
             NET-SNMP
             mmap = shared
             lock = fcntl
             nonblock = fcntl
             idle = idled


Thanks, Garry