Can Thunderbird by configured for new unified folders other than the ones provided by default?
For example, my profile has a "Spam" unified folder, but the only Spam folder showing up there of my ~10 IMAP accounts is one from Gmail. How can I get my other 9 IMAP Spam folders to show up under that node in the Unified tree?
Another example, say I have a folder per account called "Receipts". Is it possible to setup a unified folder for that?
I have tried marking folders as Favorites and even added folders to "Search" to the unified folders. The first didn't help and the second caused all folders to be listed but not as a sub-folder under the unified node in the tree. However, my "Spam" node doesn't appear to be a true unified folder, but a shortcut to the Gmail folder.