Google webMail Filer for Thunderbird functions like a Gmail uploader, but it also includes additional flexibility and power. It works by scanning a root folder, looking for Thunderbird mailbox file, then allows the user to select from them for upload with the same name of the mailbox as Label, yet with an optional Override Label. Do not worry about existing messages, Google webMail Filer for Thunderbird will never upload a duplicate copy of your email. If a duplicate is found, it is only assigned your chosen label. The program is designed to work with as less disruption as possible, with Pause / Play / Cancel controls for each sync job you carry out.