[Exim] exim -v option failure

I have tested my exim installation and when I issue (as root):

max:/# exim -v bosse@???
testing
ctrl-d

it replies:

LOG: MAIN
<=root@??? U=root P=local S=254
max:/# LOG: MAIN
==bosse@??? R=localuser T=local_delivery defer (13): Permission
denied : creating lock file hitching post
/var/mail/bosse.lock.koechel.nu.3cc57cc7.00001820 (euid=1000 egid=1000)

Can someone help me with my setup?

Thanks,

/Bo