does lda_save_to_detail_mailbox exist?

[A. Schulze]

Hello,
there is a nice feature in lmtp to save messages to user+foo@domain in  
INBOX/foo
Looks like that doesn't work as good if lda is used.

I have
  dovecot-2.2.13
  mail_location = maildir:%h/
  lda_mailbox_autocreate = yes
  lda_mailbox_autosubscribe = yes
  *lmtp*_save_to_detail_mailbox = yes

messages to user+foo generate an error and are saved to INBOX not  
matter if INBOX/foo exist or not:
Dec  4 09:40:59 mail dovecot: lda(u...@example.org): Debug: Effective  
uid=10020, gid=10020, home=/var/mail/u...@example.org/
Dec  4 09:40:59 mail dovecot: lda(u...@example.org): Debug:  
Destination address: u...@example.org (source: user@hostname)
Dec  4 09:40:59 mail dovecot: lda(u...@example.org):  
msgid=<3jtWlm3FCHz52KG@localhost>: save failed to open mailbox foo:  
Mailbox can't be created
Dec  4 09:40:59 mail dovecot: lda(u...@example.org):  
msgid=<3jtWlm3FCHz52KG@localhost>: saved mail to INBOX


# doveadm user -u u...@example.org
userdb: u...@example.org
  home      : /var/mail/u...@example.org/
  quota_rule: *:bytes=1000000
  master_user: u...@example.org

# doveadm mailbox list -u u...@example.org
INBOX
INBOX/bar

Possible, that *lda*_save_to_detail_mailbox is simply not implemented?

Thanks,
Andreas