Lots of email

I have a couple clients with large mail storage requirements.

If we mount an additional drive whose job it is to store these clients’ message stores, is it as simple as this:
mkdir /big/home/example/var/example.com
mv /chroot/home/example/var/example.com/mail /big/home/example/var/example.com/
ln -s /big/home/example/var/example.com /chroot/home/example/var/example.com/

Any security or other operational issues to concern myself with?

Is there a wiser approach?

We are running Centos 6.5