[Dovecot] dovecot-keywords problem with MDN

Hi all, I have Dovecot 1.2.13 installed. My clients ask why Disposition-Notification is requested every time the mail is moved on a new IMAP folder...

I take a look into dovecot-keywords file and I see that:

1. I have only one row 0 NonJunk

2. dovecot-keywords file is not present inside every directory.

How I can restore normal status? Where is probably the problem?

Thanks Mauro D.