When one has nested folders in a Thunderbird account the notification of unread mail is not being propagated up to ALL the folders in the chain to the head of the nest. My Thunderbird often does not mark the account when new email has arrived. When It does mark the account, all the folders underneath are UNmarked so one has to go on a fishing trip opening each containing folder until the unread email is highlighted. eg: An Account is sometimes marked as having unread email folder1 (no marking) subFolder1 (no marking) subfolder2 (no marking) subSubFolder (sometines marked) email is marked as unread folder2 subFolder1 subFolder2 subSubFolder3 folder3