Sometimes when you use IMAP to access e-mail from multiple e-mail clients, like Outlook and Thunderbird, some mail folders show up while others do not. This is due to IMAP “subscriptions” - the client tries to automatically pick the right folders but usually fails. Here are fixes:
Outlook:
Uncheck the “Show only subscribed folders” box found at the bottom of the window.
Thunderbird:
Go to File > Subscribe.
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