[Dovecot] failed with uid Permission denied

Hi Does somebody know the workaround I have some users, who are able to log in to dovecot but others not.... even the failpermissions in directories are same. Also mbox folder is excatly same mail

Some settings in /etc/dovecot.conf

first_valid_uid = 500 last_valid_uid = 1500 first_valid_gid = 500 last_valid_gid = 515

default_mail_env = mbox:~/mail:INBOX=/var/spool/mail/%u

So the "someuser" is able to log in but "testuser" not log from testuser logging in

somehost imap-login: Login: testuser [193.x.x.x] somehost dovecot: chdir(/home/guest/testuser) failed with uid 893: Permission denied somehost dovecot: child 8729 (imap) returned error 89

Any idea???