Would that be a folder inside Thunderbird or outside Thunderbird? Here is how to select several messages: http://xenos-email-notes.simplesite.com/417754237 However if you want to organise them in some useful way, you could look at using filters to select and move messages based on their content, sender or subject. The QuickFilter bar could also be useful in selecting multiple and related messages. If you want to export them from Thunderbird then this addon may be useful: https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/ To create a new folder inside Thunderbird, select an existing folder and right-click it. I would suggest that if possible you do not make subfolders in the Inbox. I file all of my messages that need to be kept. I keep my Inbox and Sent folders empty; anything in them is considered "pending" and awaiting being put into its rightful folder. I couldn't cope with the chaos of all my messages being in one disorganised heap.