Extra Folder Columns

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wót NK Moller dnja Awg. 23, 2015 · trajny wótkaz

When updating T-bird I got this message: "Not available for Thunderbird 38.2.0" I have many mailboxes and archive folders. For overview I need to see by a glance how many emails there are, read and not read, in each mailbox and folder. This addon has shown to be exactly what I need and therefore I have had it on for about ten years.
Can you tell me when it will be avaliable for this new version of Tbird? Why can't it allways follow T-bird's updates?