.imap folders

My user account is located at /usr/home/elise and has a subfolder ./mail In that folder I have some subfolders/subdirectories. What happens now is that dovecot creates all kind of .imap folders in these subfolders. They are all exact mirrors of the base folder(s) the .imap is part of.

Can you tell me how I can prevent that dovecot creates these .imap folders other than in my home user folder /usr/home/elise and the /usr/home/elise/mail folder?

/Elise