[Dovecot] Warning about NFS but using local fs for INDEX

[Herbert Gasiorowski]

I am playing around with dovecot and want to use local filesystem for indexing.
But whenever I open a new imap connection the following warning is shown:

Apr 30 10:14:42 beira dovecot: Mailbox indexes in /app/home/gasi are in NFS 
mount. You must set mmap_disable=yes to avoid index corruptions. If you're sure 
this check was wrong, set nfs_check=no.

/app/home is a NFS mounted filesystem, but I want dovecot to use 
/export/dovecot/gasi for indexing (See namespaces below).
I shurely can follow the hints(nfs_check=no), but I am not shure if I did
something wrong or maybe someday will change the configuration and forget to 
enable the nfs check.


dovecot version: dovecot-1.0-1.2.rc15.el5 on CentOS 5.0 (with all updates).

[root at beira etc]# dovecot -n
# /etc/dovecot.conf
syslog_facility: local6
login_dir: /var/run/dovecot/login
login_executable(default): /usr/libexec/dovecot/imap-login
login_executable(imap): /usr/libexec/dovecot/imap-login
login_executable(pop3): /usr/libexec/dovecot/pop3-login
mail_executable(default): /usr/libexec/dovecot/imap
mail_executable(imap): /usr/libexec/dovecot/imap
mail_executable(pop3): /usr/libexec/dovecot/pop3
mail_plugin_dir(default): /usr/lib/dovecot/imap
mail_plugin_dir(imap): /usr/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/pop3
namespace:
   type: private
   separator: /
   location: mbox:~/Mail:INBOX=/var/spool/mail/%u:INDEX=/export/dovecot/%u
   inbox: yes
namespace:
   type: private
   separator: /
   prefix: #home-tmp/
   location: mbox:~:INDEX=/export/dovecot/%u
auth default:
   passdb:
     driver: pam
     args: imap
   userdb:
     driver: passwd