[exim] Permission denied:

Hi,
I installed Exim 4.34. I'm running MEPIS (debian). All the mail I
recieve, internal or external is being defered. This is a sample from
the msglog:

2005-01-25 06:26:59 1CtOqU-0000bJ-Ko <= root@??? U=root P=local
S=766
2005-01-25 06:27:00 1CtOqU-0000bJ-Ko == muz@muz-linux <root@???>
R=local_user T=mail_spool defer (13): Permission denied: creating lock
file hitching post /var/mail/muz.lock.Muz-linux.41f62d04.00000957
(euid=1004 egid=8)

What is the Permission I have set incorrectly?

Muz