[Dovecot] Is dovecot NFS safe?

I'm migrating our mailserver from cyrus 2.0 to Postfix and Dovecot.

We're using maildirs delivered to /var/maildir, which is mounted via NFS from a Netapp. My understanding was that maildir was completely happy in an NFS environment but I've seen a couple messages here recently which mention the dovecot index files not being NFS safe.

Are their any caveats or gotcha's that I need to be aware of?

Thanks, Adam.