En août 2015, j'ai eu une mauvaise surprise… des répertoires IMAP ont simplement disparus de mon client thunderbird

En fait, ils étaient simplement “cachés”

Solution tirée de http://superuser.com/questions/392320/how-can-i-force-thunderbird-to-reload-imap-folder-structure

Click on the account line in the folder tree (the line just above the Inbox)

You should get a screen of options, find Manage folder subscriptions and click on it

• Click the Refresh button
• Close the folder list window
• Click the little triangle at the top level of the account in the folder tree to hide the folder list
• Click it again to show the folder list