I try to specify the Folder properties for a folder that is located on a remote IMAP server. In particular, I want to set "Act on new/unread..." to unticked, and I want to specify the default identity for replies to messages in that folder.
KMail accepts the changes in the dialog and everything looks fine when I close the dialog with OK. However, there is a popup message from the system tray with a text like this (in Finnish; I am translating this back to English):
<Name of IMAP account>: Some remarks were not written successfully to the IMAP-provider with regard to "Folder name". (Joitakin merkintöjä ei onnistuttu kirjoittamaan IMAP-palvelimen kohteeseen ”INBOX”.) SetAnnotation failed, server replied: A001353 BAD Command Error. 12

My interpretation of this message is that the IMAP server on this account does not want to store on the behalf of KMail whatever settings I have picked on that dialogue (or the settings get lost somewhere in Akonadi?).

I report this as a bug because:
(a) If the settings are not set, then the KMail dialog should not close normally when I click on OK.
(b) I do not see why this would have to be served on an IMAP server, and that you can expect every IMAP server to store this type of information on KMail's behalf. In my view, these settings are local to my KMail - e.g., I may not even have the relevant "reply identity" set up on another system from which I read my IMAP.

Also, the KMail dialog box remembers the new settings for a while, despite not saving them, but when I restart KMail the settings are forgotten. (It reverts to something that seems to be the "default", i.e. "Act on new/unread" is ticked, "Use default identity" is ticked, the rest is unticked or unset.) This is inconsistent.

Reproducible: Always

Steps to Reproduce:
1. With an IMAP server (I have tried two different IMAP servers, one running MS Outlook, the other running something called OX or so), set up an account in KMail (or using an existing IMAP account).
2. Right-click a folder on the IMAP, select Folder properties
3. Change a setting, I have tried "Act on unread..." and "Reply identity"
4. OK.
Actual Results:  
KMail appears as if using the new settings, but it forgets them on a restart.

Expected Results:  
KMail should use the new settings and remember them. Or alternatively give an error and not accept the changed settings.

If this setting is stored by some, but not all IMAP servers, then the storage backend of KMail should store the setting unless it can be stored on the server. These are, after all, options that are unlikely to be used by other email clients.