I use Sonic's webmail site at work (they block SSH - I usually SSH into the shell server at home).
One thing I've noticed is that all the IMAP folders I have (about 20) aren't refreshed unless I log off and log back in. Only the currently displayed folder is. So if I want to see if I have new mail in one of the folders, I have to either select it, or log off/back on. Even reloading the page in the browser doesn't seem to trigger a re-read of the folders.
Does anyone know if there's a setting that will make the webmail client reload all the folders (either on a schedule, or when I reload the browser)? Or is this a server configuration item I have no control over? Or can it be done at all?