[Dovecot] maildir file creation problem

this is my first post on the dovecot list. i have been using postfix with uw

i am getting the email bounced back with this message and i think it is related to dovecot or a permissions issue.

thank you.

maildir delivery failed: create maildir file /dev/null/Mail/Dovecot/tmp/1212763230.P4560.izmail: Not a directory