Retreiving folders size from clients

[Jean-Christophe Delaye]

Hi,

We're using cyrus server with quotas on top level user's mailbox.
Quotawarn is set to inform user when the the limit has been reached.
When the user is warned for quota size over limit, they'd like to look 
how big their folder are.

It looks that some imap client can do it (Outlook), and others not 
(Thunderbird).

I wonder if there's a standard way for retreive folders size from the 
client side ?

thanks

JC