extra IMAP folders: how to make all clients use the same Sent folder?

Dear All

I have just setup IMAP with Maildir, but unfortunately some clients create their own folders instead of using those specified in 15-mailboxes.conf . What could be the reason?

Here's what it looks like:

B list "" *

• LIST (\HasNoChildren \Sent) "." "Sent Messages"
• LIST (\HasNoChildren) "." Gesendet
• LIST (\HasNoChildren) "." Entw&APw-rfe
• LIST (\HasNoChildren \Trash) "." Trash
• LIST (\HasNoChildren) "." Papierkorb
• LIST (\HasNoChildren \Drafts) "." Drafts
• LIST (\HasNoChildren \Sent) "." Sent
• LIST (\HasNoChildren) "." Ausgang
• LIST (\HasNoChildren \Junk) "." Junk
• LIST (\HasNoChildren) "." INBOX B OK List completed.

Here for example "Gesendet" (meaning "Sent" in German) is a folder created by some Android client app. This app uses it to store its sent mail, while another client uses the Sent folder.

Also, is it correct that all those folders (both pre-made and extra) get created directly in the user's maildir, alongside cur, new, tmp and Dovecot index files? Shouldn't there be any subdir?

# dovecot --version 2.2.13

Thanks! Stanisław