[SOLVED] User vmail

[HSorgYves]

What I did is:
more /etc/passwd
…
vmail:x:1002:8:vmail-user:/home/vmail:/bin/false
usermod -u 300 vmail
find / -user 1002 -execdir chown 300 {} \;
Then I checked the following files (as suggested by joximu):
* /etc/postfix/main.cf
virtual_minimum_uid = 2000
virtual_uid_maps = static:300
* /etc/courier/userdb
(empty)
* /etc/ispcp/courier/working/userdb
(empty)

Two questions are remaining:
1) Why is virtual_minimum_uid set to the uid of vmail and not to 2000 in the main.cf of postfix?
2) Do I need to change /etc/ispcp/ispcp.conf as well?