[Dovecot] create mailboxes in /var/mail via doveadm

[Radim Kolar]

what usedid is used by doveadm for creating mailboxes? can it be setup 
to run as dovecot:mail?

cant create mailbox from command line
ponto# ls -ld /var/mail
drwxrwxr-x  8 root  mail  24 Apr  5 20:35 /var/mail

ponto# doveadm mailbox create -u jboss INBOX
doveadm(jboss): Error: Can't create mailbox INBOX: Permission denied

mail_location = maildir:%h/Maildir:INBOX=/var/mail/%u