[Dovecot] error 89 Failed to create storage with data

Hello,

I have this error message in logs : dovecot: Nov 07 21:49:34 Error: POP3(manager@mydomain.com): Failed to create storage with data: manager@mydomain.com dovecot: Nov 07 21:49:34 Error: child 27834 (pop3) returned error 89

When I try to retrieve email of manager@mydomain.com kmail says there is no new message although this email box is not empty.

I don't understand why. In my dovecot.conf I have default_mail_env = maildir:/home/Courrier/%d/%n with mutt on the server I can read all emails in /home/Courriel and for example : /home/Courrier/mydomain/manager/

Does anyone have an idea where I have to look for ?

Thank you for your help and your response

Nicolas