[Users] Claws-Mail will not show every mail folder

[Jonathan Hooverman]

Dear List,

I am subscribed to the email service of T-Online.de, which I access via
IMAPS (Port 993, SSL/TLS) with claws-mail (3.9.1).

When I access this account via web interface, it will display these
folders:

Posteingang (Inbox)
Sprachbox (Voicemail-Box)
Entwürfe (Drafts)
Gesendet (Send)
Spam (Spam)
Papierkorb (Trash)
Queue
Xing (folder created by myself in the web interface)

Claws-Mail will only display these folders:

Inbox
Sent
Drafts
Queue
Trash

I have tried "Rebuild folder tree" and "Check for new folders" but I am
still missing some folders (Sprachbox, Spam, Xing).

Do you have an idea, what might be the problem and how to fix it?

Jon.