Postfix warning - create file maildrop Permission denied

Problema riscontrato nell'invio di posta tramite webamil:

[root@zion vhosts]# tail /var/log/maillog
Aug 23 15:48:15 zion postfix/postdrop[18637]: warning: mail_queue_enter:
create file maildrop/575635.18637: Permission denied
Aug 23 15:48:25 zion postfix/postdrop[18637]: warning: mail_queue_enter:
create file maildrop/576016.18637: Permission denied
Aug 23 15:48:32 zion postfix/postfix-script[18759]: warning: not owned
by group postdrop: /var/spool/postfix/public
Aug 23 15:48:32 zion postfix/postfix-script[18760]: warning: not owned
by group postdrop: /var/spool/postfix/maildrop
Aug 23 15:48:35 zion postfix/postdrop[18637]: warning: mail_queue_enter:
create file maildrop/576412.18637: Permission denied
Aug 23 15:48:45 zion postfix/postdrop[18637]: warning: mail_queue_enter:
create file maildrop/576891.18637: Permission denied
Aug 23 15:48:55 zion postfix/postdrop[18637]: warning: mail_queue_enter:
create file maildrop/577268.18637: Permission denied
Aug 23 15:49:05 zion postfix/postdrop[18637]: warning: mail_queue_enter:
create file maildrop/577665.18637: Permission denied
Aug 23 15:49:15 zion postfix/postdrop[18637]: warning: mail_queue_enter:
create file maildrop/578053.18637: Permission denied
Aug 23 15:49:25 zion postfix/postdrop[18637]: warning: mail_queue_enter:
create file maildrop/578454.18637: Permission denied

[root@zion vhosts]# postfix check
postfix/postfix-script: warning: not owned by group postdrop:
/var/spool/postfix/public
postfix/postfix-script: warning: not owned by group postdrop:
/var/spool/postfix/maildrop

SOLUZIONE:

/etc/init.d/Mailscanner stop
killall -9 postdrop

[root@zion vhosts]# chgrp -R postdrop /var/spool/postfix/public
[root@zion vhosts]# chgrp -R postdrop /var/spool/postfix/maildrop/
[root@zion vhosts]# postfix check
[root@zion vhosts]# /etc/init.d/Mailscanner start

.