Parece que mais pessoas queriam esse recurso, mas você deve perceber que as pastas do Thunderbird são marcadores do Gmail. Portanto, as tags do Thunderbird não são as mesmas dos rótulos, em outras palavras: não há uma contraparte do Gmail.
Portanto, ainda não acredito que esse recurso esteja disponível. Verificarei se consigo encontrar uma maneira de filtrar sua caixa de entrada por tags (movendo-as para pastas).
Da Base de Conhecimento do Thunderbird em filtros
Filtering based on Tags
Thunderbird doesn't have explicit support for filtering by tags but you can select Custom Headers from the leftmost list box while editing the filter rule and add support for X-Mozilla-Keys, and then test whether it "contains" that tag. Thunderbird uses that header to store tags. For example, X-Mozilla-Keys: forum fyi indicates the message has the forum and fyi tags.
IMAP accounts store tags using message attributes instead, so its not possible to do that with messages stored in remote folders. If you copy the message to a local folder it currently doesn't add a X-Mozilla-Keys header with the tags, though it will add a empty X-Mozilla-Keys header when you compact it
Aqui está um link para a Base de Conhecimento nas tags
Thunderbird has limited support for tags in message filters. It just supports set a tag as a action. However, if you add a custom header for the tag, or specify it using "Customize" in the leftmost list box you can test for tags. Since you can have multiple tags for a message its recommended you test whether X-Mozilla-Keys: "contains" a tag rather than using "is".
View -> Sort by -> Tags can sort the messages in a folder based on the tag. View -> Messages -> Tags can be used to display just the messages with the selected tag. The View list box has a similar menu command but it is not visible in the toolbar in version 2.x. Right click on the toolbar, drag and drop the View control to the toolbar, and press OK to add it. You can also create a custom view using View -> Messages -> Customize that displays just the messages with the desired tags.