Procmail and thunderbird: folder/maildir created with root as owner

Question

I have a mailserver configured(spamassassin+procmail+sendmail+dovecot) I want all spam mails redirected to spam folder I set /etc/procmail

DEFAULT=/var/spool/mail/$LOGNAME/new
ORGMAIL=/var/spool/mail/$LOGNAME
MAILDIR=/var/spool/mail/$LOGNAME

# deliver spam to spam folder
:0:
* ^X-Spam-Status: Yes
.Spam/

And mailbox for dovecot

inbox = yes
  #mailbox name {
    # auto=create will automatically create this mailbox.
    # auto=subscribe will both create and subscribe to the mailbox.
    #auto = no

    # Space separated list of IMAP SPECIAL-USE attributes as specified by
    # RFC 6154: \All \Archive \Drafts \Flagged \Junk \Sent \Trash
    #special_use =
  #}

  # These mailboxes are widely used and could perhaps be created automatically:
  mailbox Drafts {
    special_use = \Drafts
    auto = create
  }
  mailbox Spam {
    special_use = \Junk
    auto = create
  }
  mailbox Trash {
    special_use = \Trash
    auto = create
  }

When i send a spam mail for test,it not create the folder automatically on thunderbird,and i see the folder(exist on system) has root permissions instead of user permission,of course if do chown after another mail sending return to original permissions(root!)

Answer 1

Add DROPPRIVS=yes at begin of /etc/procmailrc

man procmailrc :

DROPPRIVS If set to `yes' procmail will drop all privileges it might have had (suid or sgid). This is only useful if you want to guarantee that the bottom half of the /etc/procmailrc file is executed on behalf of the recipient.

Answer 2

Solution found:

mailbox Spam {
    special_use = \Junk
    auto = create
}

became

mailbox Spam {
    special_use = \Junk
    auto = subscribe
}

Now it works