Thunderbird folder synchronization between different host systems can get out of sync at times, see below for a solution to re-syncing your folders and subfolders
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How can I force Thunderbird to reload IMAP folder structure
Whenever I create a new label in my Gmail account, this creates a new IMAP folder. Sadly, that new folder does not show up in Thunderbird unless I restart Thunderbird. This is not specific to Gmail.
Super UserOliver Salzburg