Comment 24 for bug 291827

The behavior of this bug has changed, I believe due to the patch at bug 275561.
Now, when a new message arrives for IMAP and is filtered to local folders (and assuming no other new mail) there is no notification popup. You still get the alert sound, if you have that turned on; and you get a tray icon unless you're using the 'Mark as Deleted' deletion model (xref comment 8). The tray's tooltip shows "0 new messages." In TB, clicking the tray icon (which would normally redisplay the alert box) does nothing.

However, in the following sequence, you can still see the "0 new messages" alert box:
 - an ordinary new message arrives in the Inbox and stays there; alert is shown
 - user switches to Inbox -- tray icon & account New flag are cleared, but
   message & folder New flags persist
 - new filtered message arrives before existing New messages are read
In this case, the alert box will show "0 new messages" -- but also (in TB) will list the existing New messages from the Inbox (xref bug 138631).