I have 6 differents mail accounts defined in my zoho web client. All messages are filtered and if message is moved to folder on arrive (doesnt stay in inbox) then i have no info (in folder tree, next to the colapsed account name) about number of unread messages, it shows still 0. When i click to expand that account to check it out, then i can see folder tree and unread messages.

I noticed thet sometimes even expanded account is not refreshed, because when i once checked other account and click back to see my main (of course zoho :) ) account, suddenly i see many new messages. It was not long time, about 10 seconds! I doubt it that during 10 seconds i got about 5 emails.