I think you need to look at permissions on the place where you store the mailboxes.
Your /etc/imapd.conf will tell you where the mailboxes are stored. Make sure the directories are owned by cyrus:mail. Mine as an example: cat /etc/imapd.conf | grep -i default # Which partition to use for default mailboxes partition-default: /var/spool/cyrus/mail tjk@debian:~$ ls -la /var/spool/ total 12 drwxr-xr-x 12 root root 1024 Feb 3 10:20 . drwxr-xr-x 18 root root 1024 Feb 2 21:15 .. drwxr-xr-x 5 root root 1024 Jul 11 2001 cron drwxr-xr-x 3 root root 1024 Nov 7 21:28 cups drwxr-xr-x 4 cyrus mail 1024 Feb 3 11:55 cyrus tjk@debian:~$ ls -la /var/spool/cyrus/ total 5 drwxr-xr-x 4 cyrus mail 1024 Feb 3 11:55 . drwxr-xr-x 12 root root 1024 Feb 3 10:20 .. -rw------- 1 cyrus mail 98 Feb 3 13:09 .bash_history drwxr-x--- 23 cyrus mail 1024 Feb 3 18:36 mail drwxr-x--- 26 cyrus mail 1024 Feb 3 10:20 news *-------------------------------------------* Theodore Knab Systems Engineer *-------------------------------------------*