My kolab INBOX somehow had its write permission removed. When this happened I could no longer trash or move messages from my INBOX folder. It would be nice if KMail had somehow shown me with a visible clue that my folder was not writable. How about putting "(Read-Only") next to the folder sorta like you do when the account is offline with the "(Offline)". Reproducible: Always
So a Kolab Inbox is a folder that should be writable, in normal situations
I will not add it :) Because example in my kolab account I have more than 30 folders in readonly I don't want to add it for each folder. For account it's more easy just at toplevel.