No.. but thanks to your post and thanks to the davidep post now i understand why from 2 year ago every six month users of my server are blocked (they use the shared folder service, samba) until the admin insert again the password using the password change.
I thought it was an ldap db corruption !
From nethserver documentation:
"The system will send an e-mail to inform the users when their password is about to expire."
If a user don't have an email ? If you are not using the mail server on nethserver ?
Who receive the mail ?