I have a Queue folder in Thunderbird. I put messages manually in there, and I would like all of them to be in unread status, whether I have read them or not. Like force to be unread all the time. How can I do that?
Mozilla Thunderbird is built on Mozilla's Development Platform and has the same Add-On Extensions capability that Mozilla Firefox has.
I don't think there is a way to do what you want to do natively, but if you know how to build a Firefox Extension, you could look into building a Thunderbird Extension that could monitor your folder and always mark the messages as unread.
Thunderbird Extensions extend the functionality of the application, giving programmers the ability to add additional functionality to it using the add-on architecture, which is similar to how plug-ins work.
Here is the resource center for building Thunderbird Extensions: https://developer.mozilla.org/en/Extensions/Thunderbird
I know that this question is still relevant to a lot of people. Thunderbird now has the option to mark an email as 'unread' in the 'Other Actions' menu that shows up on the right side of the status bar, above the email.