[Dovecot] default_mail_env %d problem

[Den Zinevitch]

Hi all.
I`ve got such problem:
default_mail_env = mbox:%h/mail/:INBOX=/var/mail/domain.net.ua/%n  -  it works.
But when I say:
default_mail_env = mbox:%h/mail/:INBOX=/var/mail/%d/%n - it not.
Log:
Aug  3 22:51:19 serv dovecot: POP3(user): mbox: data=/home/user/mail/:INBOX=/var/mail//user
Aug  3 22:51:19 serv dovecot: POP3(user): mbox: root=/home/user/mail, index=/home/user/mail, inbox=/var/mail//user
Aug  3 22:51:19 serv dovecot: pop3-login: Login: user=<user>, method=PLAIN, rip=xx.xx.xx.x, lip=xxx.xxx.xxx.xxx
Aug  3 22:51:19 serv dovecot: POP3(user): Disconnected: Logged out top=0/0, retr=0/0, del=0/0, size=0