Current behaviour: For some special folders like Sent, subfolders will (correctly) stay with their special parent folder in "smart folders" view. For some other folders like Inbox, subfolders will (wrongly) be removed from their special parent folder in "smart folders" view. expected behaviour: There should be no difference in handling subfolders of different special folders like Sent or Inbox. The behaviour should be consistent. As for the "right" behaviour, that's Bug 516367 - Smart folders: Don't separate subfolders from their parent (inbox) folders

Note how the subfolders of Inbox vs. Sent end up in completely different places in "smart folders" view.

A common usage model is to archive sent folder contents occasionally, in sub-folders of the Sent folder, e.g., Sent/Sent-2008, so we keep sub-folders of the Sent folder with the sent folder. But for inboxes, there are imap servers that store all folders underneath the inbox, so showing sub-folders of the inbox with the inbox would put *all* folders underneath the inbox. So this is by design.

(In reply to comment #2) > A common usage model is to archive sent folder contents occasionally, in > sub-folders of the Sent folder, e.g., Sent/Sent-2008, so we keep sub-folders of > the Sent folder with the sent folder. But for inboxes, there are imap servers > that store all folders underneath the inbox, so showing sub-folders of the > inbox with the inbox would put *all* folders underneath the inbox. So this is > by design. so bug=invalid?

There's a good reason for doing what we do - but that doesn't make this invalid; more like Wontfix. If internally we didn't treat sub-folders of the imap inbox as sub-folders, but rather, as siblings, then we could fix this.

(In reply to David :Bienvenu from comment #2) > A common usage model is to archive sent folder contents occasionally, in > sub-folders of the Sent folder, e.g., Sent/Sent-2008, so we keep sub-folders > of the Sent folder with the sent folder. But for inboxes, there are imap > servers that store all folders underneath the inbox, so showing sub-folders > of the inbox with the inbox would put *all* folders underneath the inbox. > So this is by design. More precisely, it's by design to avoid problems for some kinds of IMAP accounts. The same design however creates problems for POP accounts, where subfolders of Inbox, Sent, etc. have *always* been deliberately created by user, so we can safely assume user wants to have these subfolders included in the respective unified folders too. Iow, the design for POP and IMAP accounts could and should probably be different, per David's comment 4 here and his same comment in Bug 516367: (In reply to David :Bienvenu from Bug 516367 comment #5) > Perhaps the way out of this is to handle the imap servers require imap > folders to all be under the inbox as if all sub-folders of the inbox were > actually top level folders, and then we can satisfy the pop3 users who want > sub-folders of the inbox to appear with the inbox.

I am also affected by this issue. In my use case, I have multiple accounts, both POP3 and IMAP and explicitly use subfolders on both Inbox and Sent with automatic filters moving new messages from Inbox to subfolders of Inbox based on sender. I find the Unified Folder view highly useful since it allows me to set up filters for the master Inbox where it only shows unread and starred messages. I would also like subfolders of Inbox to attach to the account's main Inbox folder while in Unified folder view, in the same way as subfolders for Sent currently do and as requested by original bug submitter. Maybe it could be configurable, either in the UI or perhaps through Config Editor since it can be problematic for certain IMAP setups (but not all as my use case details).